With a former boss, we subbed to an EC that had lots of warranty business. Co. called him, he called us. I guess we made a little $ from it, but seemed we had to justify every minute of time & material. Call to approve this, call to approve that. Having to get into someones packed closet to get to the attic hatch didn't compute when justifying time spent on job. They usually wanted us to swallow travel time or a supply run, etc.
I now a plumber who says he makes good $ with a warranty co.