How many can you manage by yourself?

[Byran Parson]

Every person will be different, but how many properties have you found to be manageable to manage by yourself?  At what point did it become too much along with your full-time job?

I'm planning to buy 10 rentals over the next 10 years (looks like I'll have the cash to do it).  I easily manage 2 rentals that I currently own.  However, what does it look like when you get to 10 or 12?  Have you done it?  Looking for any thoughts...

I'm handy enough to do work myself, but when there's 10 or 12 properties, that's not going to be feasible.  But even with setting up contractors to do the work, it takes time.  Also will take time to screen tenants, deal with vacancies, 3 a.m. toilet leak calls, etc.  

My father-in-law started a paving business years ago and he describes the point at which he wasn't able to "manage it all himself" and had to start hiring/outsourcing his back-end work.  That's my general question about rentals...