In the same way that the Dewalt right-angle drill attachment is a niche tool that's really only useful for confined spaces, 3M's 150-grit "SandBlaster" sanding sheets are only something you'd spring for over regular sandpaper when you need something that can easily bend and contour without losing its grit or original shape, whether its wet or dry. They also tend to last longer, which is great.

A 4-pack of these sheets is $7 on Amazon.