This gets even crazier because the IR's themselves influence so much of the texture and response you get, so it's not just about the EQ differences between cabs. That is to say, when I change cabs, I change settings at the amp to accentuate what I like. This makes it pretty ineffective to dial in a tone and just cycle through cab examples... well, shouldn't say ineffective because its a fine place to start, but it's certainly incomplete.
All I can say is I have maybe 10 IR's I like per goal. Squeaky cleans, pushed cleans, saturated classic power amp crunch, or fire breathing watt monsters, inside of those categories I have maybe 5-10 "go to" IR's. This is what I draw on when I need to spend my time learning/playing vs. exploring.
When I don't have a deadline, I go exploring. I dial an amp in for the mood I'm in, then I cycle cabs. When I find something special, I switch modes and cycle amps through that one cab to really "learn" it and what it brings to the table. I get a TON of practicing done across many genre's as I work through the cab list, lemme tell ya so I don't really mind that it's a pretty slow process
To me EVERYTHING is all about the IR. I leave the amp controls at noon and find the IR that suits the amp, then adjust to taste with amp controls .