I can't comment in detail about how the scheduling and postponements are taking place, but cases are postponed for multiple reasons. It could be that security screening is not ready for the hearing. It could be for an actual justice and fairness matter, when applicants, claimants or their counsel are not able to come to a hearing, or for operational, internal reasons, such as if the decision-maker at the IRB is sick or unavailable.
Then the IRB proceeds with the postponement, and it's up to them as to how they schedule this, in light of all the other claims they have scheduled.