Outsourcing DFD is really up to you. I would never outsource DFD because of how much of a perfectionist I am. What I mean is that I would go through EVERY SINGLE house in the zip code & dead end areas where most people doing DFD might not go. I have also just finished DFD with an average of 20 hours per week for the past 3.5 months (Aug 13th). I made it my part time job. Hence how I have time to be here on BiggerPockets to contribute.
At the same time, your eyes distinguishing the not so obvious distress condition on the property like overflow in a mailbox, broken window, bent garage doors, tarp over car, talking with neighbors etc would require someone very devoted seeing, like I said, EVERY SINGLE property that way.
If you have the time I recommend doing it yourself because even if the numbers from your research of the areas make sense, when you're there in the area you'll clearly see that the numbers might not look like what you thought the area would look like positively and/or negatively. It can also be costly paying someone for the gas since constant braking and going with 3-point turns, u-turns, etc really does use up so much more gas than you think than driving on a highway or how most people normally would. It would eventually come down to the cost per lead as well.
I've got a solild 1-1.5% conversion ratio when calling and mailing to the homeowners. FYI
