Oh totally, I'm not exactly a "Geoff said do it this way. This is the way!" kind of guy. I can't tell you how many variations of his programs I've "made" and run - some worked, some didn't.I think there is wiggle room in the GIANT
Changing time caps can definitely increase variability in number of sets, and sometimes getting more sets by extending the time will help you compress the rest periods of the other sets. I was playing around with that with a Strong! spin off, and by the time I was working triples I was working on compressing rest periods on doubles, and by the time I was working on 4s I was compressing rest periods of 3s. Whatever the highest rep range I was working on I was using a "fixed" rest interval of on the 3 minutes, so each "heavy" day got longer, while the "light" day (heavy day minus one rep) kept getting faster and shorter.I think varying the session length could at times lead to faster progress due to the increased variability.