This appears to be another reflection of the managerial role that Chief Justice Roberts plays:
He does the relistings to ensure ample time to determine that a to-be-calendared case is not going to be pulled for some foreseeable reason after the schedule is set.
He does the 'Cert - Summary Dispositions' so, without wasting too much in the way of Court resources, he can return a case to the appellate level and say "we decided a new case recently and want to make sure that this new decision doesn't change your mind about what you previously decided."
Strikes me as a bit of a bean counter, but I like the philosophy.