I have asked AEA about this multiple occasions, half-hour is considered work time, and has to be included in computing work time during rehearsal.
The best thing to do, to maximize time during tech periods where half-hour is given is the following:
1) Give them 30 minutes half-hour, take five, and then move on to your 80 minute work session.
2) Or, be very clear with the cast that during tech/rehearsal periods with costumes you will give then 25 minutes to get them into costume, then give them a five minute break, and then start. Trust me, if you are working with any sort of "older/experience" actors, they will fight you on this . . . thinking the half-hour is all sorts of sacred - when in reality, the half-hour call is really just tied to a lot of rules around performance.
As far as the AEA rules are concerned, there is no half-hour until you get to paid-public performances. In reality, tech rehearsals are just normal rehearsals. It's considered standard to give the cast 30 minutes to get into hair, costume and make-up, but in reality, if it only takes your actors 5 minutes then that's what you need to give them. If you make it clear to the cast that your expectation is for them to get into hair, make-up and costume in 25 minutes, and then give them five minute break, and start 30 minutes after the call - then life goes on. I usually announce at the top of the half-hour that I expect them to be ready in 30 minutes, plus take a five minute call - and then adjust the calls to to the break, announce the break, and then call them back.
Let us be honest, how many of us going down and check with actors in during half-hour during tech, to see actors sitting down, chatting until like ten minutes before they are expected onstage. Usually, I have more the enough to do on stage during tech that I don't feel like I am losing time, but there has been techs were I have told the actors - ten minutes to get into costume ASAP, and we start on tech.
Now, if you are doing a run, or show, you only have to worry about the break at intermission, so it doesn't matter how long the it is between breaks. (Like, my actors on my current show have 2 hours and 35 minutes from fight call thru half-hour to intermission).