How long do you continue to put into your Vacancy/CapEx/Repairs?

[Casey C.]

I know the "emergency fund" for your investment properties varies on your comfort level, experience with the market and number of doors you have. 

My question revolves around capex/vacancy/repairs. From what I've seen on the podcasts, people put a % of rent away to cover for those costs. At least that's what Brandon does. 

What I'm curious about is how long do you continue to contribute into this? Is there a threshold where you stop after you've reached a certain point, or do you contribute until you're able to cover the cost of the purchase price? Also, does this amount change as your portfolio grows, or do you do have funds for each door/property you have?

Thanks!