Experience...that's when I finally realize what I am able and not able to accomplish.

I opened a Kodak/Schneider Retina lens once to look for a sticky 'dynamic' DOF arrow problem. I realized I needed a third or fourth hand to get it back together, put everything in ziplock baggies, forgot a few things, panicked & opened the second lens to refresh my memory...then there were two bags of parts. I did not open the 3rd lens.

Now I have some cool high quality junk found optics to experiment with, like a coated achromat or possibly cemented triplet (it's so fat and has multiple edges), about 50mm diameter & 250 mm f.l. Why, that's perfect to experiment on a Speed Graphic with!

Somebody once said, "Good judgment comes from experience, and a lot of that comes from bad judgment"

...and doing the same things expecting different results has been defined as insanity by many people...and proven by more.
happy holidays

One way to keep parts from going astray is to get a piece of tightly woven indoor/outdoor carpeting or felt and do the assembly and disassemly on it. It helps keep dropped parts from bouncing away. Another idea is to build a felt lined tray with slightly raised edgesto work on. You cand glue felt on to an old cafeteria tray.

I use a large white t-shirt type cloth, or an actual t-shirt rag depending on whether cleaning an old dirty mess of a job or working on a minty shutter. I don't like fiddle edges because I lean my elbows down a lot to steady my tolls and fingers etc...
Parts stay put and wehn dropped pretty much stay where they land, but the ones that can fly are a problem. What do you think, Mosquito netting???