Not sure I even understand the question to be honest. You are looking to change the allocation rate based on a group of VMs in terms of CPU overbooking. This is not an option right now, and I don't expect it ever will be. The closest you could come is creating resource pools and assigning shares accordingly, or doing this on a per VM basis with shares is also an option if you don't have the DRS license. But it gets complex rather fast.
if you are not seeing contention / performance issues, I wouldn't touch it. If you are, then changing the shares could be a way to solve this.
