Transmission Repair

You are making sense, Joe.  We advertise "our estimates are written in stone" and we stick to that.  I've posted this before, but here it is in our promo video.
Although I've never actually calculated how much we win, or lose, on each job.  I just looked at the monthly/quarterly/yearly totals and compared them to my production payroll numbers.  I would adjust up if we were losing but I seldom adjusted down.  I believe that it's easier to do with transmission repair than it is with general repair.

This post is slightly off-topic, but I feel there's a lesson I could pass along.
We've discussed transmission repair as being a transactional "one and done" event.  While we don't sell the customer for their next major transmission job per se, we do sell and schedule the customer for their next ~10-day recheck.  Our service writers never had a problem with doing so. This is not only to road test and check for leaks, but it was one of the stipulations of our 5-year/100K mile warranty.  A minor leak today could turn into a major transmission repair tomorrow.  It would be on our dime, too.  
Something for shops to consider is having a BBB-sponsored arbitration text box on the warranty document or repair order.  Check with your local BBB and see if they could help.  Our BBB required the BBB arbitration clause to be in a separate text box prominently displayed on the front of the RO or warranty.  If they sign the RO/warranty, the customer will receive our 5/100K mile warranty.  If, for whatever reason, they don't want to sign the warranty, then they get our 1-year/12,000-mile warranty.
 By signing the text box, if a disagreement arises, the customer is giving up any legal means of remedy in favor of a BBB-sponsored neutral arbitration.  We never had a problem with it, nor did anybody want to use the BBB as an arbiter.  Below is our BBB text box disclaimer.  The shop named below is the shop we sold our business to.

I've come to the realization that I don't need to play with individual stocks.  Rather a mutual fund or an annuity.  If I've got my math right, our retirement savings will last for at least 30 years.