I have a similar problem, but most of my time seems to be tied up in just... noodling around, I guess. I know for a fact that I can build many things on my car very, very quickly. I do it every year when I suddenly realize "oh man I forgot to fix that one critical thing and I'm leaving on a road trip in 5 days"! But when there's no time crunch, things take me FOREVER.
I think my general procedure is: put the car up on jackstands. Wander around some. Crawl under the car, forget the light, go get the light, find something interesting on the bench to play with. Get reminded that something else on the car was leaking and maybe look at that. Play with something else I found on the bench. Decide to organize the bench. Lose interest in organizing the bench and remember to crawl under the car again (with the light this time). Realize I need a wrench, go get a 1/2" wrench. Crawl back under the car, realize I needed a 9/16" wrench. Take a nap under the car instead of crawling out to get the new wrench. Wake up 30 minutes later, get hungry, get some food. Wander around the house. Go back under the car but this time bring the whole toolbox. Get my arm stuck against the chassy while trying to get a tool out of the toolbox. Realize how dirty the undercarriage is because now it's all over my arm. Go get the Simple Green and detail the undercarriage. Realize I still haven't actually done what I was going to do. Look at the weather for tomorrow and see that it's supposed to be nice; decide to do the work "later" on a "gross day". Repeat process periodically, once every few weeks, until 5 days before the road trip... at which point I will actually fix it.
Man, thank god Jane is very infrequently in need of major repairs!