Most SM contracts have a table called schedule B. It is a list of charges for various work they may do for the OC.
My experience is that some SM are more vigorous than others in applying these charges.
It’s all legal what they charge because it’s in the contract the OC signed.
It’s often a point that OC don’t understand when they appoint a SM.
On the other hand , it’s not a bad idea to ask the SM to justify ever charge., in case they are being a bit liberal in their charging
I’m going through a situation where a former SM for our property seems to have overcharged the OC, and now can’t justify their charges.
Watch this space