Given that chip manufacturers visit our site quite frequently, this is our advice.
First of all, it would be nice if WiFi chips would decrease the beaconing rate the more neighboring nodes they have associated with (in IBSS mode); many neighbors -> beacon rarely. They could consider the default beaconing rate for 1 neighbor, increase the interval to 2 times the default if there are 2 neighbors, to 3 times the default if there are 3 neighbors, and so on.
When the adapter is in Ad-Hoc mode, it already knows how many associated neighbors it has (either the adapter knows or its driver knows, depending on the architecture of the chip/adapter). Just adjust the beaconing rate at the points of association/disassociation procedures.