It may interfere with your recovery or it may not. If getting an extra rep or two gives you jolly's, then go for it. If you're doing what your supposed to do, in the very near future, you'll have absolutely no desire to even consider an extra rep.
Sometimes on my 3rd set of an exercise if I can get a 6th or 7th rep I do it. Am I being stupid? I don't completely go to failure, but say I am doing Press if I can get that 6th rep it is like it helps me psychologically for the next workout because I think I did 135 last time and got a 6th on the 3rd set so I feel more confident on 140. I never do an extra on my 1st or 2nd set and I know you will probably say the weight is too light if I can do an extra, but I think I started at an adequate spot. Thoughts?
It may interfere with your recovery or it may not. If getting an extra rep or two gives you jolly's, then go for it. If you're doing what your supposed to do, in the very near future, you'll have absolutely no desire to even consider an extra rep.
If I've been sick, injured or been on vacation or something, I often do a slight 1-10 kg deload (depending on the exercise and nature of the time off) just to have a somewhat easy point to start back from. I do the same thing often in those instances, though never for squats and deadlifts, I feel I have to psych myself too much up for a certain number of reps, so I'm done after those 5 whether I would be able to do more or not.
From personal experience I might add.. Maybe your form is spot on, but if you're not sure, consider expending the energy while you can perfecting form to better ingrain the movements. For example, make sure you're hitting parallel or a little lower on Squats and shrugging hard at the top of Presses. Paying strict attention to proper setup for the pulls now will pay dividends in the future. Sets of 5 reps made to seem a little more difficult concentrating on "perfect" form now will probably do more to extend your LP than those extra reps will, IMHO.