Some people are technically inclined and enjoy testing equipment just for the fun of it. That's me. But my testing is not to see how sharp my lenses are. I know how sharp they are. What I enjoy is seeing how the new lenses perform versus the old manual focus ones or just how good are those old lenses. Most of my testing is on Nikon's manual focus lenses and at that different versions of the same lens.
I guess testing has become a hobby for me and is rooted in my profession. I'm a retired electrical engineer and spent about 10 years as the quality control manager of my company. My job was always fun.