I actually haven't completed the game once yet, but I've made a new file at least 8 times. I have like 24 saves since for each file I make 2 saves in case I save over one of the wrong ones (And luckily for me, I had a second save when I saved over my main file on accident) and I made a few checkpoint saves before I do something highly risky or do something possibly gamechanging.
I've done one main file, first one being at level 27. The next one was a female character using guns. Next was an Energy Weapons based character. Next was Melee/Unarmed, and I made a few other ones for fun that used any weapons. My most recent one is going to be my level 30 character and the first one I'll beat the game with. Doing House quests.