Are you trying to say you want to do as many pull ups as possible? Like work your way up to 30, and hell even after that, 35, 40, etc...
Well if thats your goal, then train for your goal. If you want to do alot of pullups, then train by doing alot of pullups.
My suggestion would be to do as many pull ups as you can on Day 1, take sufficient rest the next day (i.e. leaving your back alone) and on Day 3, repeat by doing as many pull ups as you can. By doing this, your training for endurance, and recieving rest.
And remember, bodyweight too exercises are related to your actually bodyweight (go figure, lol). The less weight your pulling up, the more youll be able to crank out. Its hard to pull up a spare tire is what im saying.
Hope this helps.
-Kyle