@notmyname Listen to your body. I would do them at least 2 times per week and If I feel exhausted, I recover with good nutrition and rest.
Also every rep has to be qualitative.
We don't know how you do the pull ups.
Maybe the execution is fine and maybe it's not.
If you can't pull yourself up, do negatives and hold against the drag.
Fibres need contraction, exhaustion and burn. You also need a lot of good local energy in your muscles, else you won't feel pump and stronger than the previous session.
Rows on the dip bar after your last set of pull ups, is also helpful to increase your reps.