Re: Wearing through tennis trainers.
Most shoes have a 6-month durability guarantee. Just return them.
I usually purchase 4 pair at a time from a large on-line retailer. I can burn through 3 or 4 pair in that 6 month time period. I then return them to the retailer and they give me store credit. I use the store credit to buy new shoes.
Repeat above every 6 months.