I like to use sandpaper because...
I then know for a
fact that there will be no surprise slickness at all anywhere on my tires.
But even more importantly... I get to give the tire and it's installation a full final inspection on all degrees before trusting it completely.
(I've found it's more fun to ride when you know it's not going to fail) I'm sure that there's some great guys inspecting and testing them at the factory, and I'm sure they take good care of them in shipping and handling and stocking at the shops. But with all of that I'm still considerably more sure in seeing closely first hand every angle of the tire on the rim before I ride.
No surprises. Now don't get me wrong I'm not an anal personality at all. But it only takes me about 15 minutes per tire... and the
feel good factor for me personally is a relatively huge payback!
...........
After getting the wheel mounted up right... I only go over the tire about two times around getting a nice even roughness from edge to edge. That takes about 5 minutes. Then I look it over. Rub my hand over it. Maybe hit a spot here or there that may not be consistant. And then I go one more round with longer strokes to finish it up. Again looking it over. Never have I found any abrasives left in the rubber from the sandpaper. But than I don't use the sandpaper from the Dollar Store. Besides... the abrasiveness of most riding surfaces are more likely to get stuff embedded into the rubber.
and then...
I got my new tires on.. every bolt is tight.. all the rubber is sticky... No more questions... just ride!
Edit:
Oh.. and I also take it easy for the first 25 miles or so...