Yungerman, thanks for pointing out the different ways of defining 6 hours.
These opinions are based on the fact that it says ??? ???? (I think in the Rambam). Literally, that means “like 6 hours”, so some say it just has to be almost 6 hours or “into the sixth hour”.
I hadn’t mentioned those opinions in my post, since my posts were long enough, and I was just explaining the different shitas regarding how many hours to keep without going into specifics of how people define 6 hours.
So I appreciate your pointing it out. I would just add though that if someone doesn’t have a specific minhag, they probably should not keep less than 6 full hours on the clock until and unless they ask a sheilah and are told otherwise.