Eh, 3 is the happy medium for me.
You can set up and manuever with 2 of them with 1 being the base of fire and the second being the manuevering/flank element. This also then allows them to change resposibilities on the fly if something changes.
The 3rd squad is a reserve element which provides fire, but moves to assist either squad in either pushing the target into the L or fortifies the assault element. At any given time with keeping the 3 squads positioned with the flow of the enemy (or countering additional enemy forces entering the fight from another direction) you can play off each other via simple comms.
Anything smaller and its a logsitics/fire superiority issue. Any larger and you start having too many moving pieces for a SUT type of operation.
Only thing I'd add is a vehicle for a blocking element, because I always love dismounted infantry panicking and basically allowing the blocking element to push them all right into us.