ORIGINAL: tiemanj
I know I'm a little late to this party, and this may have been answered already... but naval support squads can drastically increase the unloading rate. If he puts them on an amphib (I always do), he can unload the bulk of the xAKs / xAPs the next day. Also (for my invasion at least), the support squads unload last, so all the combat power is on the ground first.
I wouldn't plan on a long exposure time. Another thing to add to the calculation is that it will take you a minimum of 4 days to respond to an attack - and 6 if he takes the base. 1 day to move there (minimum), 3 days to unpack, 2 days to march over good roads to the adjacent base if you don't want to risk unpacking in a hot hex.
As to shipping, he can boost his effective shipping by only packing up the combat elements of units for the first wave and leaving support squads back (Pearl, Coal Harbor, Kodiak, whatever). He can always bring them in the second wave (or even fly them in). I'm not sure of the Japanese OOB, but for the American one, using this method, you can effectively double the combat power you can land on D Day.
Overall, I like the idea of keeping powerful units in a strat mode reserve to quickly deploy where they are needed. But there are limitations to CONOPs. If he goes in fast and reckless (and I don't mean that in a bad way) he can upset your timetables.
Alfred has always said the game is about strategic movement (and least I think that is what he says). I would argue it is about time. Time from detection to destination, time to unload, time to move, time to unpack, time to set up the next layer of defense. Fall behind anywhere, and the next one is incrementally harder.
But he will still have to unload the NavSupport before he can benefit from them. I have zero experience with Japan (or doing amphib landings from xAP/xAPs for that matter. All my experience is based on APA/AKA landings. And (as you well know by now) its not always that easy to get everything unloaded on the first turn. Would be pretty amazed if Japan could unload as fast using xAP/xAKs. Then again as Loka says if the Japanese IDs are that much lighter...
As you say he can probably get the combat troops unloaded reasonably fast but the support troops would be another ball game. And without those his abilities for sustained combat would be much weaker.
I think a NORPAC invasion is getting more and more unlikely by the minute. Going by SIGINT his IDs are packing up and leaving one by one. Probably for India!
can´t hurt...
