There are plenty of groups for patrol. It's when you need the patrol planes for other things that it seems like a shortage. Most of the PA groups divide and can be used all over the map.
This is true.
But with their great capacity, the Emily in particular, it's so tempting to use them for Transport duties... which I know you've done, obvert. So Netties and Jakes have to plug the search/patrol hole, which is fine but not quite as great.
H8K2 is a trap. Placed there to ruin any JFB with its lures. It has range, speed, guns, torpedoes, radars, max load... All the goodies. It does anything you want and does it well. So what if you have occasional operational casualty, one or two shot down by cap or flak and few downed by LRCAP over that convoy.
Before you know it, you have increased production first to 20, then 30, finally 50 planes/month and still need more to get your Emily fix.
Then it is 1944.... And you have used 800 H8K planes and realize; "Boy, I could have equipped entire fighter air army or built an aircraft carrier with those 115'000 HI points...."
I will resist... No more extra Emilies into production nor any -L transport models, not a one extra 4E built as Japanese and those that are produced are used just for primary mission and that only. Or perhaps just this one night raid deep behind enemy lines... Just this once...