50% Rule for Single Family Homes?

[JP Ivey]

This is my first post.

I have been doing a lot of reading over the last several months and am trying to decide what niche I want to become part of.  Here is my question:

Does the 50% rule apply to single family homes?  If so, how are they a good investment at all?  In a decent neighborhood in San Antonio, there is no way I would find a home that met that requirement.  In my head, I feel like single family homes would require less maintenance and effort.  Am I missing something?

Thanks

JP