There is a fine line between to much friction, nice sliding movement and slop.
Are you talking about printers or something else here? 
Haha, ya printers.
I was printing some PLA LM8UU bushings so that’s where this came from.
I would say that “nice, sliding movement” IS a fine line between too much friction and too much slop.
You do have that in a better order than i did. That’s why they call me the " Junk Shop Engineer "