I've experienced "tacit..feelings" personally on many development projects. I'm not sure why this path is better than the other path, but it just feels better

I've experienced "tacit..feelings" personally on many development projects. I'm not sure why this path is better than the other path, but it just feels better to me. One example is where to put new code. Do you put it in the existing code (monolith) or do you create a "service" for the code? Sure, some things are pretty straightforward but sometimes there really is a toss up of where this new thing should live. The problem is when someone asks me why, I can't really explain it and it gives less weight to the decision. However, looking back I can say that I've been more right than wrong, so I guess I have that going for me.