Me again,

The manufacturing no. is PCW8203W2A (with no space between 2 and A)

The replacement belt I use has part no. H40200A (don't recall actual
manufacturer) which is direct replacement for part no. 28808 (same
number of found on amana.com: item no. 28808 - BELT,AGITATE SPIN)
available from a local appliance repair centre.

It isn't a 'plain rubber automotive belt'. It does have a V-shape
(well, not really a V, since the inside of the belt is flat, not
pointed, but the belt does have tappered sided) and is covered in some
kind of cloth material, which is what rips and shreds first, after
which the inside rubber section starts cracking. I'm assuming it is a
low-friction belt with this cloth material covering the rubber.

I'll verify the drive pulleys as suggested for alignment/rust/wear.
For alignment, I don't recall seeing this in the repair manual. Is it
easily done visually?

Thanks,
t

I own an Amana clothes washer, model
CW8203W2, purchase ~9 years ago.

I never had a problem until about 3 years ago
when the drive belt started falling apart.

I replaced it with a stock replacement

What do you mean by a "stock replacement"?

Not a plain rubber automotive belt I hope. Many washers these days use
special low-friction belts which can not be replaced with just any old
belt.

I'll be replacing it yet again in the next few weeks,
but I was wondering if there is any adjustment
required to ensure these belts last longer. What
could be causing belts to fail so quickly?

Installing other than the factory replacement would be one cause, too
much play in the idler or transmission pulley another. Maybe a
deformation in one or the other as well.