Restricting adhkar and supplications to a specific number which is not mentioned in the religious texts comes under the heading of innovation (bid‘ah)
Question

Is it anywhere mentioned in the Quran or the Hadith that certain DUAS should be recited for (X) number of times or during certain time of day for the most benefit? For example reciting dua for indebtness during Maghreb and Fajr for 7 times for the most benefit than other times during the day. I personally believe that a person can recite ANY Surah, Ayaat, or Dua for as much as they want and during any time of the day. Am I correct in this?.
Praise be to Allah.Firstly:
The adhkar and supplications which are mentioned in the Qur’an and Sunnah are of two types: restricted and unrestricted.
Those which are restricted include those which are restricted to a particular time, such as the adhkar to be recited in the morning and afternoon, and before going to sleep and when waking up, and adhkar that are to be recited after the prayer, and so on.
The restricted adhkar also include those that are restricted to a particular number of times, such as the tasbih, tahmid and takbir to be recited after the prayer, or before going to sleep, and so on.
With regard to this type, the Muslim should adhere to the time at which they are prescribed, or the number of times which they are to be repeated according to the Sunnah, and he should not go against that, if he is keen to truly follow the Messenger (blessings and peace of Allah be upon him) and attain the reward for reciting this dhikr.
The second type of adhkar and supplications is those that are unrestricted. This includes those which are mentioned in the Qur’an and Sunnah and we are encouraged to recite them, without restricting that to a particular time or a particular number of times to repeat them.
The Muslim may recite this type at any time he wishes, and repeat them any number of times he wishes.
But he should not change them from unrestricted to restricted, and commit himself to saying them at a specific time and at no other, or commit himself to saying them a specific number of times, no more and no less.
Restricting something that was prescribed as unrestricted is contrary to what the Prophet (blessings and peace of Allah be upon him) prescribed for us, and means that the Muslim is falling into innovation without realizing.
The scholars of the Permanent Committee for Ifta’ said:
The basic principle with regard to adhkar and acts of worship is that they are tawqifi (i.e., they are to be based solely on Qur’an and sahih Sunnah, with no room for personal opinion), for Allah is not to be worshipped except in the ways that He has prescribed, whether an act of worship may be done at any time or is limited to a specific time, or it is to be done in a specific manner limited to a specific number of times. So with regard to what Allah has prescribed of adhkar, supplications and other acts of worship without specifying a particular time, number of times to be repeated, place or manner of doing it, it is not permissible for us to commit ourselves to doing it in a particular manner or at a particular time or a particular number of times. Rather we worship Him by doing such acts of worship without any restrictions, as they were prescribed.
With regard to what is proven on the basis of religious texts or the practice of the Prophet (blessings and peace of Allah be upon him) to be limited to a particular time, a particular number of times to be repeated, or a particular place, or is to be done in a particular manner, we worship Allah by doing it in the manner proven in the religious texts. End quote.
See also questions no. 3927 , 88102 and 128455 .
Secondly:
With regard to the supplication for paying off debts, you did not state which supplication you mean. Several hadiths have been narrated concerning that, including that which was narrated by Abu Dawud (1555) from Abu Sa‘id al-Khudri, who said: The Messenger of Allah (blessings and peace of Allah be upon him) entered the mosque one day and saw one of the Ansar whose name was Abu Umamah. He said: “O Abu Umamah, why do I see you sitting in the mosque when it is not the time for prayer?” He said: Because of worries that have overtaken me and debts that I owe, O Messenger of Allah. He said: 
He said: Yes, O Messenger of Allah.
He said: “Say, every morning and afternoon: Allahumma inni a‘udhu bika min al-hammi wa’l-hazan, wa a‘udhu bika min al-‘ajzi wa’l-kasal, wa a‘duhu bika min al-jubni wa’l-bukhl, wa a‘udhu bika min ghalabat id-dayni wa qahr ir-rijal (O Allah, indeed I seek refuge with You from worry and grief, and I seek refuge with You from helplessness and laziness, and I seek refuge with You from cowardice and miserliness, and I seek refuge with You from being overwhelmed with debt and overpowered by men).”
He said: So I did that, and Allah, may He be glorified and exalted, took away my worry and paid off my debt for me.
This hadith is da‘if (weak); it was classed as da‘if by al-Hafiz Ibn Hajar in Nata’ij al-Afkar (2/376), where he described it as gharib. It was also classed as da‘if by al-Albani in Da‘if Sunan Abi Dawud.
For more information, please see the answers to questions no. 197480 and 71183 .
Even though the hadith is da‘if with the wording and story mentioned above, we may note that the supplication is restricted to a specific time, namely morning and afternoon. Apart from that, there is no restriction in terms of the number of times it may be repeated. There is nothing in the Prophet’s Sunnah to indicate that it should be restricted to seven times.
We reiterate that this supplication, without the story mentioned and without restricting it to a specific number of repetitions or a specific time, is something that is soundly narrated and proven from the Prophet (blessings and peace of Allah be upon him) that he said it. In fact it is proven that he said it a great deal.
Al-Bukhari narrated in his Sahih (6369) that Anas ibn Malik said: The Prophet (blessings and peace of Allah be upon him) used to say: “Allahumma inni a‘udhu bika min al-hammi wa’l-hazan, wa’l-‘ajzi wa’l-kasal, wa’l-jubni wa’l-bukhl, wa dala‘ id-dayni wa ghalabat ir-rijal (O Allah, indeed I seek refuge with You from worry and grief, helplessness and laziness, cowardice and miserliness, and being burdened with debt and being overwhelmed by men).”
It is prescribed to recite this prophetic supplication and, in fact, to say it a great deal, but without restricting that to morning or evening, or reciting it at a specific time or repeating it a specific number of times. Rather you should recite it a great deal in your prayers, when you are alone, in tahajjud, and so on.
Another hadith is that which was narrated by at-Tirmidhi (3563) from ‘Ali ibn Abi Talib (may Allah be pleased with him), according to which a mukatab (a slave with a contract of manumission) came to him and said: I am unable to pay off my contract of manumission; help me.
He said: Shall I not teach you some words which the Messenger of Allah (blessings and peace of Allah be upon him) taught me, and even if you have debt the size of Mount Sir, Allah will pay it off for you?
He said: Say: Allahumm akfini bi halalika ‘an haramika wa aghnini bi fadlika ‘amman siwak (O Allah, suffice me with that which You have permitted so that that I have no need of that which You have forbidden, and make me independent of means by Your bounty so that I have no need of anyone besides You).
This hadith was classed as hasan by al-Hafiz Ibn Hajar in Nata’ij al-Afkar (4/127). It was also classed as hasan by al-Albani in Silsilat al-Ahadith as-Sahihah (266).
It is unrestricted in terms of the time it may be recited and the number of times it may be repeated.
What you mentioned is correct with regard to this supplication, for the Muslim may say it at any time he wishes and repeat it as many times as he wishes.
And Allah knows best.