Yes, you can setup a schedule. In 7DOT/7mode you could only run them on the hour and the limit was 8 concurrent.
You can create new schedule or use existing ones. We setup a bunch of them, every two minutes for a few hours. Most run in a few seconds, we have been this in 7mode for 2 years, 400 volumes, it has saved us about 252TB. We only run this on volumes that don't contain DB, all or NFS.
To create a new efficiently policy:
volume efficiency policy create -vserver xxxx -schedule xxxx (you can -duration if you want it stop if it's been running too long).
We have it working in cDOT for a new months on 8.1 no problems so far.