I tried introducing a group of four yellowheads into a 300 gal tank with a 3" sandbed (fine sand, with lots of 'puka shell' sand added for a rubble source). The dominant fish killed the other three. I didn't have success with my group, though my remaining jaw lived for about three years after that.
I introduced them all at the same time - all were active and healthy at the time of addition. three burrows were built, the nasty fish never bothered to build his own, he chased the others out of theirs as part of his abuse.
jayo