Would 10 days Vipassana a waste of time, if not practised afterwards? People who have done 10 Days of Vipassana Meditation retreat 5 to 100 times often say that from 5th day the Mind becomes very subtle &amp; remains 24 * 7 like that.
However when they're back to their families &amp; life an average normal lifestyle.
The Mind becomes similar to what it was before (in most cases, as per my experience).
Is our Mind is similar to any other muscle of the body, The bodybuilders can come back in shape quicker than someone who has never achieved it before.
If someone is doing the vipassana 1st time &amp; someone else has a good experience.
Would a 10 days vipassana a waste of time if not practiced after?
Anything we strive to attain in life takes practice. Mastery signifies being able to perform not only in ideal circumstances, but amidst the chaos of everyday life. Ironically, one can become attached to the feeling of being (or striving to be) detached. This can become a serious obstacle if we start dividing practice opportunities into preferences.
How do we counter this? Though from another tradition, I can think of no better quote than one of Dogen Zenji:

we do not sit in order to become enlightened; we sit as an expression of enlightenment.

What he meant was the Buddha did not require any external factors for his enlightenment. Once he realized that trying to force his mind and body into attainment was not the way, he found the Middle Way, a balance between discipline and natural flowing.
Thus, Attainment is not something we can forcibly will or strive into existence. Like mastery in any art, it needs to flow naturally from practice. The mind being subtle is still just the mind. The mind being rigid is still just the mind. Learning to see within those two states is equally worthwhile and necessary.