The stamina mechanic itself is fine. It does need to be sped up more and the feats need to be less grindy. I get that it’s supposed to be a challenge but having to repeat the same battle against the same squad over and over again just to get a feat gets old really fast.
Plus the whole “premium” ticket thing is just a cash grab. The way CG has decided to update the mode has sucked all the fun out of it. If anything it makes me more reluctant to spend money on the mode, which I suppose is opposite of what a company should be aiming for.