How do you underwrite repair, maintenance, vacancy and capex?

[Aaron Jones]

So I'm sure this question has been posed many times, but I can't think of a good way to search for it so... When I analyze a deal, I generally assume 25% of gross rent as reserves for any rep & maint, capex, and vacancy.Then I throw in 10% for property management. All other expenses (tax, ins, landlord-paid utilities, etc ) are calculated seperately. Is that generally the approach most investors take? Are these percentages realistic, aggressive, or too conservative?