For NEET PG, I think a range of 6–12 hours of consistent studies over 6–9 months is enough to get a good score in NEET PG.
I am a graduate of private medical college. In my first attempt of neet pg, I got 38k rank.
I took a drop ( which started off as a 10 month drop but converted into a 18 months drop).
But however due to repeated postponements, I fell off track multiple times, and so effectively I studied about 9 months.
on good days and specially during the initial times, I would study 10–12 hours a day.
But on days that I would be low and not very enthusiastic, I would force myself to study upto 4–6 hours a day.
i think more than the hours, Its about consistency. 6 hours a day for 3 continuous month can give you better results than 12 months of occassional 12 hour sprints.