It's like having a personal mission statement. Everything in your life will fall into a category and can be easily dealt with.
If you know certain things that you will NOT bend on, it will make future decisions EASY. You won't have to labor over decisions if you have a personal resolve. It can be likened to a belief system. If you live in accordance with what you believe in your heart, you will be balanced and live a whole, full life without guilt.
I, personally, have resolved to NEVER cheat. I will not even cheat on Solitaire. So, whenever I am faced with a situation where I may believe I can "get away with" cheating, I will not hesitate to decline. This saves me time and keeps me true to myself. This eliminates the fallout of "What if...."
By the same token, you can have a list of things you will ALWAYS do. One of the things I always do is give people the benefit of the doubt. I try to always believe the best motives instigate the behaviors of others. Until someone proves me wrong, I will always believe the best about them. This, too, saves a lot of time.
That being said, NEVER and ALWAYS, while being absolute words, in my system are relative. If I am playing against a cheater, I can use the power of right to prove them wrong. If someone I trust betrays me, I can stop giving them the benefit of the doubt and become wary of them.
This fits in with my belief system and decision making process. There are variables in our dynamic world that need to be taken into account when making our personal lists but notwithstanding, deciding these things beforehand can make us stronger and more effective, giving us more time to focus on other more important things.