I hope you or someone is at least keeping an eye on your properties for break ins, squatters, roof leaks, temperature control, frozen pipes (if in cold climate), if you have a basement and sump pump goes out leading to water damage etc.I just talked to two investors in California that have let their properties sit vacant (no mortgages so paying property taxes and insurance).

A roof on the 600K property will cost more than on the 300K property, but you have more roofs to repair on the multiple 300K properties.

Large basement and attic space, new roof and some of the kitchen is already torn out from the current owner. one bedroom does have a closet that will need built. plumbing seems fine, maybe a couple angle stops to change.

I also want to clarify that I do still keep a decent amount of cash - just not enough to cover every single property roof at the same time if that ever happened for some reason. 

It also kills two birds with one stone: an investment property, and a roof over your head. 

Needs more cosmetic work than major rehab, and roof was recently replaced.

You have the mortgage, taxes, insurance, maintenance, capital expenditures (roof, flooring, etc.), and also need to consider the cost of vacancies or bad tenants.I also recommend you charge market rate, for yourself and the tenant.

I assume 15% of the rent for regular repairs and capital expenses (roof, furnace, windows etc.) and 5 % of the rent for vacancies.

Then roof starts falling. 

I recommend establishing a reserve fund for major turnover expenses, capital repairs like a roof replacement, etc.