Ive used UC a few times and like it. It works best, for me anyways, at speed 5 with a 5" pad. 6.5 is too big for a pc.
The look of that paint kinda looks like you are using a QD on the pad as you polish. After the pad is primed, with polish, i only add like 3 dots on the pad. I make about 3 passes with the pc (on speed 5) and wipe off.
UC doesnt need to break down, so it doesnt matter when you wipe it off, well, unless its become dry buffed. So i might wipe it off technically alittle early. Saves me from repolishing out some dry buff marks.
Im not a fan of alot of pressure using the pc. I think it corrects just fine with slightly more then the weight of the machine. With a hard 5" pad, the pad spins nice and polishes as good as a pc gets, all without causing more damage to the paint, and causing clumping polish.
There is no rule that says you need to always add more product when moving onto a new section either. If you feel you have to much product on your pad and are ready to move on., then do an 18"x18" section, even if onluy for 2 passes. Wipe down and add more polish.
anyways , im rambling