How to set a default value for a Django Form Field, that would be saved even in the absence of user initiated changes?
I don't think there is a premade solution for you.  You'll have to do one of two things:

When the form is submitted, examine the value of the field in question.  If it is equal to the default value, then ignore the result of has_changed and save it.  (Be aware that this could result in duplicate items being saved, depending on your schema.)
When the form is submitted, search for an existing record with those field values.  If no such record exists, save it.  Otherwise do nothing.  (If these records contain a last-updated timestamp, you might update that value, depending on your application.)
When looking for this feature, one is flooded under answers pointing toward the Form initial member.
Yet, by its design, this approach would not save anything to database if the user does not change at least one value in the form, because the has_changed method returns False when only initial values are submitted.
Then, if one were to override has_changed to always return true, the behaviour would be to try to save forms for which no value (nor initial nor user input) is found.
Is it possible to have a real default value in Django: a value that the user can change if he wants, but that would still save the form to DB when the form is only submitted with default values ?