What is the longest time you should go without applying Minoxidil for MPB before benefits subside?

The  half-life of topical minoxidil in the scalp is approximately 22 hours and is significantly  shorter with the oral ingestion. Therefore,one should not stop minoxidil. Some transplant surgeons request discontinuing  for a few days prior to surgery and commencing quickly afterwards. Minoxidil does not affect 5 Alpha reductase and therefore one needs to continue to suppress the  ongoing miniaturizing effects on the follicles.

Ideally you don't stop minoxidil, and typically results after stopping and resuming after a long period of time are not as good as they are if you never stop.Yes, you will get differing opinions on how long to stop minoxidil after a transplant.  The concern is that you can damage/dislodge grafts massaging minoxidil into the scalp right after surgery.  After a week this should not be an issue.  Best to follow your surgeon's advice on this.

One should ideally not stop minoxidil for more than 1 week every year. Results are better twice daily than once daily (for men) which emphasizes the importance of sending these hairs a message EVERY 12 HOURS. There is no simple rule. Men who use minoxidil regularly get better results than those who don’t. Minoxidil only needs to be stopped a few days before surgery. Minoxidil is rarely as effective after long breaks.

When planning on using minoxidil after a hair transplant, you should wait at least 2 weeks when all of the crusting is off