I think the HCH2 tends to allow more IMA assist when there is a higher SOC in the battery.

Trying to get to (or maintain) a high SOC may be good for FE when you expend the SOC, but building the SOC through regen or forced regen ahead of this tends to be inefficient and wasteful.

I think some here would say it is optimimum to minimize both regen and IMA assist