cant realy answer that one, i never worked it out either. what i do now is just not plan anything after it, no driving, nothing that actually matters. so i dont have to decide when its done.

@Jake yeah thats the bit i got wrong. felt completely fine, got up, was ready to call it done, and then i was sat back down again. it wasn't dramatic, just clearly not finished. so one good patch wasnt the end of it for me..

I wouldn't lean on feeling fine on its own as the marker. It tells you how you are right then, and im not sure anyone is a good judge of their own alertness when alertness is the thing being judged. So if there's doubt, wait rather than test it, and don't drive. Not medical advice, and if it's a worry about you specifically rather than general curiosity, thats one for a doctor rather than for us.

yeah ok that lands. i wanted a clean signal and there isnt one, idk. annoying but fine