As an extra data point, and I don’t have my bib info offhand, but I put in a 2:06 POT for last years DL half and ended up in corral B. However, I also put in a 8:00-10:00 min estimate for the 10k and was placed in corral D for that race. Assumption is that so many people marked themselves as having a <8 min pace that they had to back up the rest of the corrals. Not sure what the split was, if I had to guess, they had A and B for <8 min and at least C and D for 8-10 min and I was just unlucky.
Challenge bib has been listing two corrals for the two races and I would expect that to continue.