Rental Property Expense Percentages?

[Henry Reimer]

So I am trying to refine my spreadsheet for rental property analysis, and I am trying to figure out what percentages to allocate for the various expenses that come with a property. Right now I set aside 24% of the gross rents for repairs, vacancy, and capital expenditures (8% for each one), and I have not been allocating for property management because I would start out by managing my own properties. I have recently decided that it would be a good idea to plan to have to pay for property management at some point so I wanted to put that in at 10% of gross rents. 

This is where my question comes in, if I were to add up all of those expenses that would come out to roughly 34% of the gross rents (this doesn't even include the financing and utilities allocation). So I was wondering, is this model accurate? What do experienced investors with multiple units have to think about this? Do you guys really spend 34% of your gross rents on repairs, capex, vacancy and property management?

All responses are greatly appreciated, thank you!