There's a lot of stuff that'll probably be reworked in the long run. For now I'm putting together a base to build on and will worry about balance a bit further down the line.
You should be able to do more than one thing in a day though, just not the same activity twice. It's not so obvious right now since there are only a couple of activities that require energy. I might relax this restriction in the future.
On the other hand, at the moment both mini-games can use up all your energy in one sitting. There's no reason to quit early unless you want to save energy for another activity, and if you don't quit early then you'll need to rest before you play again anyway.
Time periods also serve a narrative purpose. It'll become more important when there are time-sensitive events and a few nocturnal or crepuscular monsters in the game.