If you need tips on how to help speed the process up I can help some here and elsewhere. To touch base on doing multiple rehabs at once. As long as you didn't start each one at the exact time you should be able to have your contractors jumping from house to house. Now there may be some over lapping of trades and that's where having more then one electrician or plumber or carpenter ect come into play. Plus you should have more then one for every trade so that your not forced to have to wait for them and their schedule but instead you use the one that meets YOUR schedule.
Now of course this will take time to grow a relationship to each one of the companies you use. Besides recommendations from friends or other investors you can always try to call a builder and see who they have used in the past and how it went for them.
For when I build a new home, an addition, kitchen, smaller project ect. I have certain ones I know are better for certain projects but also 2-4 of each trade I will call to make the whole project work on MY timeline.
This is something you and everyone should work towards to keeping their project on THEIR timeline and not someone else's.