Struggling at work - looking for tips.

Trust me on this: Make a solid commitment to take 5 extra minutes on every car to double check all your work. You don't have to physically check but check in your mind or better yet on paper.
Take one of the forms that are used for checking in trade in's or a form that your shop uses for 42 point safety checks etc. Modify it a bit then make a ton of copies and use one for every car. I did the same thing once with a brake caliper bolt. It's why I stopped turning wrenches. The owner of the car hit the brakes and ended up doing a 360 when he hit the brakes for an exit. I got scared I was gonna kill someone. I still work on cars but not while being pressured to turn 30 hours in 4 hours time. This particular car should have been in the shop for 2 days, Brakes Timing belt 90,000 mile service, Tires, lower45 ball joints, and more. All in one afternoon. My service writer kept pushing me saying he needed it done today Yadayadayada.

Everyone makes mistakes and nobody's perfect but you can prevent any problems by completing a checklist on every car. IMO all shops should require a written checklist signed off on by the shop foreman. Not to be a ball buster but just to save your *** on that rare(LOL) occasion that you get distracted.

Unfortunately as you get older you get just a bit more forgetful.