Also a question. What is the optimal use of construction engineers? Don't worry about ports and airfield levels, I'm strictly talking forts. I have 3 unit groups working perimeter bases with the idea they will slowly build rear bases as they finish the front line. Should you build to level 4 forts or all the way to 6 (assuming we aren't talking about the few bases you want to go to level 9)? What is the best balance between maximum defense for each base and maximum number of built up bases? Obviously organic engineers would continue to work on forts at a slower base if we stop below 6. Thoughts?
"clusters" of 2-3 well built bases (within 2 hex, preferably 1 hex) separated by 6-8 hex (allows fighters from one cluster to support another) to upto 12-14 (allows escorted strikes). Basically a strong point defence. Build them to level 6 forts IMHO.
Level 6 airfields appear optimal, although 7 are nice. Ports are less critical as the Japanese as you don't have the heavy baggage that the Allies do in their divisions (all those Ice cream machines).
This does allow the Allies to land in the "gaps", but then they have to build them up from almost nothing... which they can do but they are vulnerable and they need to commit significant assets during this phase. Ultimately you can't really stop the Allies, so you want to inflict delay on them at every step.
A nice "chequer" style defence in depth is possible in the DEI and SWPAC, but CENTPAC is a bit harder to achieve.
As Japan I think you need to create as much depth to the defence as possible, a hard, but thin crust is easily broken, depth give tactical and operational advantages for the counter attack.
Cheers
Rob