Cam Chain Extenders

[trapshooter2]

I've got 31K miles on my 05 Nomad and am having my local shop install my cam chain extenders next week. My adjuster was measured and has fully extended at 6/16's of an inch. below the threaded unit . My question is how many more miles can I get out of my bike since the extenders will give me about a half inch of new travel?
Once the chain stretches to the maximum again I guess you have to install new cam chains and expensive proposition. These riders with 100k to 200k miles and more must eventually be putting in new cam chains once the extenders are extended to their maximum.