Some torbot skin bond will buy you a few extra days between having to change the posts. As in, the glue will last a bit longer than the back taping method. In hindsight, I don't feel the juice was worth the squeeze on the glue though. Sure it buys you a few more days, but it takes longer to clean out the ears.
I had to do practically nothing once I tried the back taping method, cleaning wise. I tried for a minimum of 10 days up, but rough play cut that time short once or twice.
Changing every 3-4 days is a complete waste of materials and time, unless your pup rolls around head first in poo or mud, goes scuba diving and gets the posts 100% soaking wet or uses the posts as spears to go old school fishing in the pond out back.
Oh, you don't have a pond out back? Well, the first two then
I had posts in through potty breaks in the rain, my other labs biting and playing and licking, etc., etc., etc., and the most that ever resulted in the extended time, compared to what others recommend, is a bit more ear wax build up. Most of the wax, however, was coated on the base on the post, which is foam backer rod. A quick wipe with some alcohol wipes, followed by a quick swipe of some cornstarch powder...perfecto, ears were good to go.
Definitely a wise idea to do it yourself, as mentioned above. Unless of course your breeders name was kim.