Often, recurring blisters have everything to do with anatomical anomalies in your feet. I have very prominent achilles tendons that don't really allow my heel to sit properly in the heel cup of most shoes. It causes friction above my heel just proximal to the achilles insertion point, especially in many running shoes. In fact, almost every pair of running shoes I use ends up with a hole worn in the cloth inside the heel collar withing a few weeks of beginning to use them.
When I choose trail runners for hiking they cannot have a high collar or I'll end up with a raw open wound in the first hour. If I choose a shoe with a lower collar and often some have the cutout in the back of the collar which creates an even lower contact point over the achilles, this seems to solve the issue.
All of the above is basically a long-winded way of saying you might need to look at your individual anatomy as one part of the contributing factors when blisters continue to be an issue.