If you have any project (personal or not, doesn't matter) that does not have proper code comments and documentation and you don't want to make one because of the effort (maybe even "wasted" effort), think again. When commenting on a wall of code to say what it does, you may find a better way of doing what you have to do, possibly increasing performance, or improving security.

I have been able to do better input sanitization for a method on a personal project of mine because of this.
Don't use the amount of effort for proper documentation as an excuse not to make one.