Talk:Showdown! Luffy/@comment-27473528-20180214011247/@comment-29682895-20180305135644

The thing is that when you find Stamina Refills from the Snails (or if you like refilling your stamina with gems) then you get much more value out of it on a higher level. You'll also have a higher stamina amount for things you can only do for 30 minutes, like Hime Turtles or some events.

I personally also think it's a double-edged sword since you'll need more and more to get a level up for the free stamina, but that's also the only downside.