Well I got out a new box of 3 x 21 120 grit sanding belts to do some
sanding on a butcher block table top, and in a matter of five minutes
I went through five of them. The glue seams would not hold. The
sander was tracking perfectly.

Admittedly, these belts while a new box had been stored for a while,
maybe 5-6 years in my shop that is not climate controlled. I have a 4
x 24 that I use most of the time so the smaller sander gets less use.
However, I thought the shelf life would be a little better.

So what is you're favorite belt, particularly in terms of sanding
longevity and shelf life?

Frank