How do you deal with the rental gap?

[Marcus Johnson]

So I've heard on this forum once before that many Landlords will have a vacant rental for 1 month after the former tenants move out so that they can clean and show the place for the next prospective tenants.  My duplex rental is on it's 3rd lease of tenants and so far I haven't had that gap, but it has come to my attention that if you continue to practice your business this way eventually you'll create a problem where the current tenants overstay their lease or you don't have time to adequately clean and repair your unit between renters.   

So the next question is if you do indeed have a month's gap between tenants, then how are you dealing with year leases where every year you jump a month.  For example if your previous lease was a year and started in July, the next year the year lease would start in August and so on.  So eventually you'll be trying to find a tenant November or December when the number of potential renters is of lowest demand.  

So what is the proper way to transistion from one tenant to another in a years lease?