[topynate]

In Israel a short refresher course is mandatory if you haven't dived for six months. IMO any reputable company should require the same.

[whymauri]

This should be mandatory for a lot of sports, honestly. Assisted climbing (lead, top-roping) comes to mind. Kinda crazy that in many gyms you can get on a wall with no verification that your belay knows what they're doing.

[izacus]

As far as I know they're mandatory everywhere, but pretty much noone checks this. If you don't sign up yourself, it's not happening.