I happen to be a rather big fan of isaac (well, until it got to the difficulty of the hidden character in Rebirth), but when you get better at it you tend to play it close call, getting in hugging distance of your enemies to ensure your shots hit, making the room clear a little faster (or that's at least how I used to play it).
That's what I thought. It barely does much damage at all, and seems more of a survivability option than something to S rank every floor, and that's just not a good way to play in the long run. Requires far too little effort and doen't get you learning those attack patterns.