My maximum stamina at lvl 120 is 365. So, with 1 stamina per 3 minutes, it takes 1095 minutes or 18 hours and 15 minutes to fill my stamina bar from 0. That means I'd need to play only twice a day to use all my stamina.

Gather points are the same for everybody: 1 gather point every 2 hours, with a maximum capacity of 3 gather points. So, to use all your gather points, you'd need to log in at least once every six hours. Few people manage that (work, sleep, etc), so logging in multiple times a day is all about cutting down on their losses by preventing their gather count from hitting the cap.
Note: the rewards from gathering are also "the same" for everybody. Higher levels don't improve the rewards, it's always 0-40 stamina (on rare occasions it might be a bit more, my personal record is 63 stamina from a gather, which happened only once), similar gold, similar seeds.

Then there's raid points: 1 raid point every 30 minutes.

The raidpoints are what many people actually plan their session around: use at least one raid point right away if there's a raidboss available, then use at least one gather point, then use their stamina, and by the end of their session, if there's any raid or gather points left, try to use those. With a bit of luck, another raidpoint should almost pop up as well because it's only a 30 minute timer, so they simply wait for that, then log off until their next session. And that a few times a day, to not let any gather or raidpoints go to waste.

The higher your level, the harder it is to let your stamina hit the cap. You're actually always short on stamina, and the moment you have enough for a map + a possible Secret Garden (so generally, somewhere between 120 and 160 stamina, depends on what maps you run), you use it, and start waiting for when you have enough stamina or a gather or maybe some raidpoints again.