Initial judging takes precedence over finals. If a judge is ready to do finals and another judge has part of the group for initial judging, you have to wait for the finals.
The judges try to space out their judging, but you can run into each other at times. Some are faster or slower and that backs things up. I've been to shows where you wind up with 3 judges doing finals one right after the other due to uncontrollable things earlier.