From: Zagreb, Croatia
As an example fortification level-1 through level-3 happen a bit faster (digging fox holes, clearing fields of fire, bore sighting weapons, setting up a few hasty obstacles, things like this do not take so long) the level-4 through level-6 probably take a bit longer on average - especially for larger bases - the level-7 through level-9 will take a lot longer.
It is still possible to build level-9s ... but not as many as quickly ... and on smaller islands we have a cap of level-6 ...
Thanks for info Joe!
If not sooner by you guys I will test this when WitP-AE becomes available... the Tinian base buildup would be good test (i.e. we know how long it took historically to build it to MAX for B-29's)...
Prior Preparation & Planning Prevents Pathetically Poor Performance!
A & B: WitW, WitE, WbtS, GGWaW, GGWaW2-AWD, HttR, CotA, BftB, CF
P: UV, WitP, WitP-AE