Shorter investment lengthes for higher ROI?

[Cliff Rosa]

Trying to figure a way in which one could essentially have less than a 50% operating expense. With the 50% rule is it true to say that every year you have your property you will incur 50% in expenses? Im thinking that over a period of about 20 years operating expenses will equal to about 50%. Usually within a 20 year period, major appliances have to be replaced, roofs etc which in turn equals about 50% in OE during those years. So im trying to hit this as a short term investment, 2 to 3 years. Is it possible to say that OE can be as little as 25-30% for just a couple years give that
1-Property is in good shape
2- Tenants are well screened
3 Property is purchased a a good price.
4. Low vacancy rates
5. Im the property manager and can do alot of "fixing"