I think experience helps a lot. There's a timing element to my game and it's ended up being unenjoyable tight for some people. This was because I tested for myself, who knew the level layout perfectly and exploited it.
If you're working on a team, you can always have your team members test it. You could also take the time once you have the minimum viable product to make a build and send it to some friends and/or family. That way you can test your delivery, get some feedback, and still continue working.