I also sometimes make small corrections after 2 hours if necessary, ignoring insulin stacking rules, but if I start to spike, or (and I think this is better if its possible) I go for a quick walk to stop the spike. But if you are having a bout of insulin resistance the stacking rules are important because the resistance can suddenly abate and you seem to get hit by all that insulin floating round in your system and it's a quick descent to hypo city. I found this out (again, how many times will I learn this?) after a week's stress-induced IR in Turkey in the post-coup witch hunt recently. I got a week of highs, followed by overnight hypos, then a roller coaster when I got out and back to UK, which took a while to stabilize.
So, like all 'rules' the insulin-stacking rules apply under some conditions but not others IME.