From what I've noticed usually the recommended no of warm up sets is ~5. This is obviously not set in stone as you mentioned in your video, especially if one's feeling stiff or sore then might do some more. However I rarely see anyone doing bigger jumps than one plate per side (90lbs, 110lbs with someone has 55s) regardless of the final workset weight. If we're talking about elite powerlifter who wants to do DL worksets with 765 (and doesn't feel stiff or sore) then he'll be doing at least 7 warm up sets. Assuming he starts at 135 and adds 90lbs each set. Even more if he does any weight more than once and takes smaller jumps as he gets closer to his final weight. So potentially 8-10 warm up sets. Is there any reason behind this other than convienience?