If you spent 10 days prepping for a single fight then you would have been better off removing collar for that fight. Also, if the only thing you are doing in a day is a single action, you are playing in an extremely suboptimal manner. I almost always try to push until I have almost no HP/MP if I'm going to read a book, and almost as recklessly if I'm learning a skill/spell. There is always a timer running out in this game, if you don't want to interact with it or you want do everything then you can turn the difficulty down to story mode. To me, the action/resource management is one of the more compelling parts of the game and it single handedly manages to differentiate it from most other RPG maker games.