My wife and I own two BTL properties.

One we mortgaged personally on a repayment BTL mortgage. It will be paid off by the time we retire.
The 2nd is a bigger property, which we made a property company and purchased it through. This is on an interest only mortgage. The objective being to maximise the rent to profit ratio.

The point I wanted to make to the OP is that we have had the same tenants all the way through. People generally don't hop about if its a nice place in a nice area. Not everyone wants to be on the property market.
We have a great relationship with both tenants, they occasionally need something and thats fine.