At the very start, I was cutting the 60mg pills into quarters, and taking 1/4 at a time, which was enough. After a few months, then it was 1/2 pills, and then whole pills, as I guess my body was adjusting to it and the need for more.
Now, I take whole 60mg pills as often as every 3 hours, if having a busy day. If I take it sooner than necessary, I can end up cross-eyed and a bit dizzy and queasy (mostly from fighting against being cross-eyed).

Not that I'm advising you to mess with the dosage on your own, but I have always found that lots of little doses serve me much better than less-frequent larger doses, with any medication, not just mestinon. The pills are scored, so maybe talk to your doctor about trying something like this? Went through a phase with lots of muscle cramping, at night, but that seems to have pretty much stopped, and think it might have also had something to do with being slightly dehydrated at night (and if your guts are running faster, like it might do, then they're taking more water out of you in the process, so an extra drink before bed is not such a bad idea).