Originally Posted by Unregistered

I don't have any immediate need for manyu, dragons or coins. What else is there to use stamina for?

If you don't have anything else to spend stamina on then go for it. I know for myself I want to be able to spend stamina on the current event, as well as manyus and dragons. I will occasionally refill stamina with a FG, so in that way it doesn't make sense to spend more stamina than you could buy.
I think I've three medaled every reissue I've played since I started or close to it, and I can tell you exactly which maps on the regular campaign I have not gotten three in yet, so I understand the compulsion for perfection. There's just a limit to how much I'm willing to spend on achieving it.