Irv,
The way I look at it is if you have the AWS hooked up to a 24 hour "ON" faucet and you have a filler valve break, or a feed line pops off the 1/4" tee, you can waste a lot of water very quickly.
My 2-cycle 30 minute access timings do limit unattended "spillage" to 1/24 of what it would have been, while giving the AWS access to 60 minutes of replenishment time per day. So far, the process has worked beautifully.
Raybo