I suspect low vacancy, decent screening, no bs with tenants, and luck have all played a role. 

Given that I now have added risk of having the tenant forever, my screening requirements got tighter (less people will qualify) and my rent at every unit goes up to compensate for the added risk.

You need to know buyer has their own money they just want to use someone else's money to buy.Big difference between someone with 500k in their bank account wanting to use an HML and a buyer with 5k to their name and putting up 1k non-refundable on a wing and a prayer.If you had multiple investors you likely should have screened your investors much harder to see who looked the strongest and could perform.

I met enough people and saw enough stats to believe that REI handles their tenant screening and property management with the same ferocious level of commitment and that's what I came for.

PadSplit is directly involved in tenant screening and placement but does not manage the property.

I have amazing analytical and assessment skills, from screening tenants to having hard conversations i.e. complaints, evictions etc.

say for example you buy a solid property, hire a solid PM, and a solid-looking tenant passes screening and moves in. 

Tenant screening (how many prerequisites were really screened before they signed the lease)G.

Were they properly screened?

Replacing the screen door and screen windows.