With me, I usually do take the worst-case scenario due to my cautious playing style 😉 Even then 180 IPCs are not the worst-case scenario, not unlocking heavy bombers at all would be (which you mentioned). Now unlocking bombers is like strategic bombing. Usually your bomber will not automatically get shot down on the 6th subsequent run – sometimes soon now or later then. I only use the “guarantee” which you stated.
Now lets say I lowered my 180 IPCs to 90 IPCs (which is pretty favorable). Will you still be willing to spend 90 IPCs for heavy bombers? Can you afford to?
It’s not to say that I won’t lock other technologies on the way, but the true gems are heavy bombers and industrial technology. What use will rockets do me if I’m Japan or Super Subs if I am Russia?