Where/how do you find your maintenance and service professionals?

[Max Dama]

Hi. 

I hope my question is appropriate for this forum!
I am a rental property owner, but also own a licensed home improvement company although I do mostly smaller handyman jobs. I have been offering my services to property management companies  and I do ok contracting for them.  The issue is that they send my all over the place and half of my time is wasted driving around --  So I have been wondering, where do landlords go to find reliable turn-over or maintenance professionals?  Do they just look up people on the internet, do they use services such as Thumbtack or home advisor?  I don;t want to deal with any of those services, tried them and they don't work for me.  Is there a forum, or a website that landlords and service professionals can exchange information without having to go through the middleman?  I have not been able to find one ... and I think it would work great, if it existed.  Let me know if you know of such forum/website and how you find your pros.  Thanks all.