50% Rule: Does this apply to Small MF (2-4 Units)

[Matthew Metros]

I am underwriting a deal and the marketing package has unrealistically low expenses. As a rule of thumb, I applied the 50% rule to meet reasonable 

I was told by another investor that small MF doesn’t have 50% expenses. It’s usually more like 30-35%. 

Should I Just have to underwrite with the given expenses to find out? Is there a better rule of thumb? I ask because I don't want to scare good deals away...