I haven’t quite finished it yet, my feeling is that it slightly overstays it’s welcome.
I’ve also noticed that most of the time I do a thing or two in the game then realise there’s not quite enough time in the loop to do another thing, but just enough time to make me want to not waste the loop, since I find starting a new loop a bit tedious.
From memory it respawns the low level enemies constantly, since they’re just ammo/health/armour pinatas. You needed to kill the big enemies to complete an arena.
Not really a fan of the design choice, but I had a decent amount of fun when I clicked with how the Devs wanted you to play.