My workout back in the day was 15,12,8,4 in reps per set and if i could do more then 4 reps i would do a 5th set. I can think of many times where things "kicked in" and i just added rediculous amounts of reps or weight in one go... i remember my squat went up 40 pounds from the week prior... it was like in week 3-4 of my first tren cycle...
I mentioning this on 'ology' when it happened, some people actually said they had the same response with their squat on tren.
Back then i remember being upset, i thought i was the only person on steroids. I would see a guy bench, squat, whatever, more then me and i would just think
"Man i suck, im cheating (doing juice) and yet that guy can lift more then i do."
But yea, there are multiple times i can think of where i would add mad weight or extra reps/sets on a workout, compared the week prior.
Now a days, because an small tendon injury, i dont go above 5 sets. I will only increase the weight one time each workout
But there were times i would do more then 4 reps, so i would increase the weight and do more then 4 reps again and increase the weight for another set, sometimes do it again... id do 6-7 sets total sometimes, for one workout.
I should also add, which probably makes a huge difference. I dont use a spotter usually so i dont push it to the limits, if i feel like i def can do another rep, i do, if im unsure i rack it... so when im feeling confident or cocky and just wanna push i may put in a couple extra reps just cause im willing to attempt them when normally im not... could be the difference for some of the times and or reps
Edit:tidy it up a bit so its easier to read