Most common causes of failures

[Andrey Pak]

I would like to find out more about why your previous real estate investment businesses have failed in buy and hold (rent) - whether it is not enough reserves, over leveraging, etc. 

In case of the reserves - is 5-10% of annual rent enough for vacation allowance?

What is the safe amount of reserves for maintenance?

Any other reserves I am missing?  

Thanks in advance, 

Andrey