Okay, first I need to preface this by saying this is all theory-crafting and I have not tried the current formulas.
Having said that, another thread made me realize that the reason I play such a super-low AIP strategy is that on Diff 10, I simply don't have the units to cover multiple systems in defensive beachheads, which got me thinking about wave size.
From patch 5.036:On Diff 7+ the randomization of wave intervals (which feeds directly into step 5 of the wave size formula) has been changed to consider the number of planets that the AI can send waves against (and thus the probable defensive power of those worlds, i.e. chokepoints, and the viability or lack thereof of smaller waves):
If there are 6+ wave-targetable planets it uses the normal (pre-5.036) formula of adding a random number from (AIDifficulty*-60) to (AIDifficulty*120).
If there are 5 wave-targetable planets the random is from (AIDifficulty*-30) to (AIDifficulty*120).
If there are 4 the random is from 0 to (AIDifficulty*120).
If 3, from (AIDifficulty*30) to (AIDifficulty*120).
If 2, from (AIDifficulty*60) to (AIDifficulty*120).
If 1, from (AIDifficulty*90) to (AIDifficulty*150) (making it actually able to hit single-chokepoints harder than it used to).
The upshot is that it makes the AI a little "smarter" about figuring out that it may as well not bother sending small waves against concentrated defenses and should just save up for stronger attack forces. Accordingly, since the AI on <7 is intentionally a bit dumb it doesn't get this new rule at all.
Averaging out the wave multiplier ends up as:
[Attack points] = [Multiplier]
6+ = 30 (Max 120)
5 = 45 (Max 120)
4 = 60 (max 120)
3 = 75 (Max 120)
2 = 90 (Max 120)
1 = 120 (Max 150)
Now, the average wave size I think looks about right, but the problem is the Max Wave size is 120 for almost all of them, and with the number of waves that attack you, you are going to get multiple waves up there at the 120 end of things so you have to plan your defences around that, which means you don't have enough units as the number of systems you are defending increases while the Wave Multiplier you are building the defences to repel stays up at 120.
Could we see the Max wave multiplier also get reduced as the number of attack points goes up? The decreasing average is nice, but we have to plan for the worst case scenario which means waves multipliers of 120 across the board.
I'm thinking it should not drop as fast as the average does, maybe by 10 per level (as opposed to the average dropping by 15) so that at 6+ systems the max wave multiplier is 80?
(Again, I have not actually played with numbers as they currently are, this is theory crafting based on numbers and my current super-low AIP playstyle.)
D.
edit: Minimum multiplier would have to adjust as necessary to keep the average multiplier about the same.