I don't have a specific testing pixel, but when I do, they're tired out by my testing them: "let's go to this community lot to see if what I did fixed it" or, "You have to go have a break, we're going to check out the routing on this lot!"

All I can think of is when I'm done the particular pixel will look at me and say, "Are WE done yet, madam? I have a life, too!"

I've had anything from a test family, to a test hood, to a full test folder.

Depends what I'm testing, but I'll usually test with minimal other CC (my regular mods + basic defaults, and whatever I'm testing). Sometimes I use them to take pictures of some new CC and I just want fast loading + easy finding in my CC.