What sort of temperature are you dealing with in your riding area, your barn area, and your general climate?
I’ve had various barn temperatures in the different places I’ve boarded and found the cooler needs changed.
If it’s cold enough the sweat steamed through the horse’s coat and condensed on the tips of the hair. In this case putting a fleece cooler on immediately after coming back to walk for the last time allowed the sweat steam to condense on the cooler rather than the horse. Walking until there was no more steam coming off the horse before going back to the barn generally meant the horse was cool and dried relatively quickly.
I have found that if the barn is too warm the horse can break a second sweat under a fleece cooler which makes drying off take even longer. I have used a wool quarter sheet over back and quarters as a post ride cooler, and I have a very thin wicking cooler (wicking Coolmax type material in a light mesh sheet - really light mesh) which I used in warmer barns.
The fastest dry time I’ve ever managed was with an old comforter in a very cold barn. I think this used the steam through and condense on the outside effect. This does need colder temps to work.