When and where I'm hunting helps me decide how long to stay on a stand, plus a bit of past experience.
Usually, the areas I hunt are very wide open, rolling hills, and I can see for a very long way
In general, I stay 15-20 minutes on a stand, but will stay 30-45 if I think it can pay off.
I generally hunt public lands in Colorado, and by Feb-March, coyotes have been called to a lot, so I will increase my time on stand to 30-45.
Every time before I stand up to go to the next stand, every time, I will glass the area before standing up. You might be surprised at how often there is a coyote standing waaay out there, looking in my direction. Then, it's game on!
I'll also glass the area before I start to call.
Conversely, on lightly hunted private lands, 15 minutes is normal.
I don't think there is a 'one-size-fits-all' when it comes to time on stand.