OnSerialize spend Message in room?

there is limitation of room message per second (500 m/s per room)

so i want to reduce it

there is 3 way to sync

1. OnSerialization call back( used by PhotonTransformView )
2. RPC
3. Player Property, Room Property


i know 2,3 is spend message in room,
but i wonder 1 is spend it or not

is it spend or not?

thank you