For a friend: loan options for 7th house

[Andrew M.]

I have a close friend who's shopping for financing on his 7th home. 

Mortgage professionals are looking for far more reserves and qualifications for this home. it was explained that this happens after you have 6 homes already. Not sure why 6 is the magic number, but anyway.... He is considering a commercial loan with an interest rate of over 6 percent. Just wondering if anyone has experience with this scenario, and if there's some other option he isn't thinking of. 

Thanks in advance!