There is no trick. I am running 70+ threads and I got skunked on the last two batches. They come when they come. A short queue will query more often and give you a slightly better chance, but the last BETA test was very small, so the chance of getting any was very small.
Cheers

Releasing...

You can improve your chances.
Set Project Limits counts and Workunit Cache Settings (Connect to network about every) such that less work is loaded than cached days.
Thus PCs will always have room for more work and ask for it often.

Paul.

Thanks for the replies. I wasn't lucky enough to get one of the work units.

Maybe next time...

1. know quickly when a beta is released, perhaps by arranging notification-via-email when there is a post to a beta testing forum.
2. Then edit your projects down to ones that don't actually have any work available. (right now there are quite a few!) I think you need to have at least one project, such has HSTB. Also increase your cache, e.g. from 1 hour to day.
3. Then in the WCG BOINC manager, manually update the project. You can do this every 2-3 minutes.

I haven't done the above in recent years, but it worked for me. I suppose it could be automated but that would be cheating, yes? Back then once there was a beta for each core that was it, because you couldn't get more until a beta finished and by then all the betas were gone. But on rare occasion the betas would flow for a day or two. That did wonders for runtime.