I don't think the subject of finger blisters, on the pouch hand, has been discussed before. I expect all of us have had a blister problem at one time or another therefore the subject needs exposure.
Here are my thoughts on the subject:
The stronger the bands the quicker the blister develops.
Blisters develop quicker when the rough side of the pouch leather is facing outward.
Long practice sessions, or too frequent sessions, can cause blisters.
Some of the things that I have tried to prevent or treat blisters:
Stop shooting at the first sign of slight irritation in the pouch finger. If I must continue the shooting, I wrap the index finger with a band-aid. Even after a blister develops I find that wrapping it with a ban-aid prevents further irritation and injury. When I anticipate a long shooting session I tape my finger before I start shooting. I have tried various types of tape but have found that black electrician's tape works as well as any. Also, the electrician's tape fairly closely duplicates the friction of the bare finger so the pouch release is not changed significantly. I have also had moderate success using a piece of thin leather attached to the middle finger (with a hole) and wrapped around the index finger.
I would like to hear about other shooter's blister problems and solutions.