ok I got a question regarding quality of the number of sets. If you know that you've done a certain amount of sets with bad form and too much of heavy weight, should you reset the number of sets again and try the sets again at a lower working weight?? or just continue to the next exercise. For example, today I tried to do weighted pullups for the very first time with 30lbs with a scheme of 4x5, i managed to hit 5 for all 4 sets but the range of motion was really poor, and i hardly got my chin over the bar most of the time. I didn't reduce the weight cuz i was an idiot. Would it have been ok to just "start over" 4x5 at a lower weight???would this have affected my strength gains?
Not during the same workout.
If the weight is already too heavy to complete your reps with good form/full ROM your muscles will be very fatigued afterwards so if you try to do another set it would be quite impossible to conclude if you lowered the weight by a sufficient amount.
Gaining strength is a very slow process, whatever you do during a single set in a single workout will have a negligible effect in the long run, i wouldn't worry too much about it.