For the time being, I have not used leverage. Sure, I have my cap rate in mind for purchasing each house and it is always high enough to make me mad: quit job right away! I will open another post for it later. To find the right cap rate, it also depends on different locations; some cities (or even just different neighbors) are easier, some others are not but you can count on their later higher house value.
Further, to be financially independent, it is not just how much you take control of money, but you may count on"山不在高,有仙則名": Using as less money as possible to get the maximum profit to reach the goal is the smartest way to go.