Can't really do reverse pullups with proper form

Hey, so I'm starting from a level I'd say is probably lower than the average person. From what I've read on here, people recommend doing reverse pullups over assisted ones, from memory because they think it helps develop better form and generally make for better progress. I've started with 5 sets of 5 with a 1 minute break between sets. My problem is that I can only really do 2 or 3 reverse pullups (in total, not per set) where I can complete the movement fully. After that, I have to basically stop the downwards part of the movement just over half way through by touching the ground. A few times I've been able to complete a couple of sets of full movements before having to switch but then the next time I go to exercise, even after rest days, my body just feels so destroyed from it that I can't even do one full one, so I think that's probably a sign that I'm going above my level there. Regardless, do you think these "half reps" are still better than assisted pullups or should I switch to those for a bit and then switch back when I've gotten stronger?