I started exactly 5 years ago and have slowly picked up 10 SFRs that cash flow $4,000/month (not including cap ex or vacancies).

Vacancy, capex, and repairs are too low. 

Should I add a flat amount in the rent, rent might go up a lot and create vacancy or should I split the amount monthly and send It to the tenant, how do I split it between a 3 bedroom apartment and an one bedroom apartment?

The other consideration would be the Capex and vacancy.

Estimated cap ex + repairs + vacancy at 20% = $1296. taxes and insurance $720. 

Any guidance appreciated Monthly Income: $5,710.00 Mortgage Pay: $2,375.84 Vacancy (8%): $456.80 Management Fee (10%): $525.32 Property Tax: $1,333.33 Total Insurance: $250.00 Maintenance Cost: $166.67 Other Cost: $16.67 Cash Flow: $585.37 Net Operating Income (NOI): $2,961.21 Downpayment - 25% ($135,000) roughly will all cost, Mortgage the rest.For the 20 years invested   Return (IRR):15.76% per yearTotal Profit when Sold:$1,059,203.90Cash on Cash Return:861.14%Capitalization Rate:7.40%Total Rental Income:$1,524,478.87Total Mortgage Payments:$570,201.76Total Expenses:$569,651.94Total Net Operating Income:$954,826.93

I try and cash flow at least $200-$300/door which doesn’t include cap ex or vacancies.

The question is - how many vacancies are you willing to have while increasing your income? 

Unless Jackson schools, it's not going to command 625 without a high vacancy rate.

Make sure the rent from the property will cover all of the expenses including the principal, interest, property taxes, home insurance, repairs and maintenance (around 8% of gross rent), vacancy (around 7% of gross rent) capex (around 7% of gross rent), and property management (unless you self manage).