Dunno what made me think of this just now. When I worked for IT in a school district way back in the 90s, a librarian told me she kept a supply of mouse balls in her desk because kids would steal them out of the school computers. What I remember about those balls was they picked up dust and crud off surfaces. Pretty soon optical mice came along and they were history.
Ouch felt that in my old bones.
Another habit I noticed was lifting the mouse so the cursor stayed still on screen, and putting the mouse down on the edge of the mouse pad, so I could move the cursor further on the screen without going past the mouse pad.
A quirk that’s eliminated nowadays thanks to mice that can adjust dpi on the fly, but I still catch myself doing this paintbrush like motion once in awhile.