Jeff,
We follow the suggested method to mix and apply. We cover the area very well, give it at least 10 minutes to dwell and then flush with water. Key for us is the extraction and flush. We have to make sure we really get it sucked out and that we have used enough water to flush it. I often will let the carpet relax for awhile, after first extraction, go clean other parts of the house, come back and extract again. Since we got a water claw, heavier areas are much easier and faster to do. Seldom have we been called back as we manage expectations upfront.
Our charges vary from $25 for one to two spots, to as much as $100 plus.
Good luck and happy holidays.
Matt