The rule WDW is currently working under is if a Standby time is 10 minutes or less, let the DAS or wheelchair user into the alternate entrance. If the Standby time is over 10 minutes, subtract 10 mins and give them a Return Time for the difference.
So yes, you can go to a ride with a 15 minute wait and be given a 5 minute return time pass. I'm officially calling these "BATHROOM PASSES". Just long enough to go for a quick bathroom break and return.
Universal uses a 30 minute rule. If a Standby is 30 minutes or less, let the disabled person in. Anything over they give you a Return Time.
I'm really really hoping Disney decides to adopt Universal's rule. (I've suggested just this to management.) Makes more sense to me and a lot less work for CMs and guests alike. But if they don't, well I now have my coveted "bathroom pass".