I eventually came to the conclusion that the way to play fes tartarus is to sneak by everything to get to the next teleport. That really sucks, but trying to kill enemies just means everyone is always tired.
I guess in p3p since they don't get tired till you leave this isn't as necessary?
It's a fine line in Fes, actually. If you kill nothing, you won't have strong enough personas, nor will your party members, to beat the guardian of the block. But the idea isn't wrong either.
The way I always did exploration in the game is if there's a shadow in the way, I'll kill it. If I can see it's a dead end, I ignore it. As I get closer to a guardian, I'll try dodging more than fighting. Hit the guardian, go down, save, go back up, see if you can kill, if yes, great, done for the night, if not grind a lil bit more. Ultimate goal is to get to the end of the current section before the full moon anyway. Always use bathrooms on days you go to Tartarus to try and get the MC in the "Great" status.
And yeah, that's one of the reasons why P3P is easier. The system is still kind of in place in that if you leave before a party member complains about being tired, they won't be tired the next day and you can chain days. Otherwise, they'll be tired for the next day, but not during explorations, so you can stay inside as long as you want.