Using Crunch Time will decrease your enthusiasm by 50%. So if you have 5, it will go down to 2.5.
Using take it easy will increase enthusiasm by 33%.
Normal will not effect your enthusiasm so no increase or decrease.
Every daily update your enthusiasm will slowly go back to 5. Ideally you want to maintain high enthusiasm, as your players will do better. So i suggest using tie, or normal. Only crunch time for special must win occasions where you think you have a chance of actually winning but not sure if playing at normal will be enough. You may even want to look ahead of your schedule and if you have easy wins or definite loss then tieing is the best thing to do.