I carried out some assessment work on Jigsaw when it was being touted to other operators. The requirement was 2 hours for recovery and return of a full crew and passengers to a place of safety - the legal requirement under PFEER. That limited the sphere of operations due to transit and recovery times.
The contract with the helicopter might well have had that recovery time in it and the remaining time after response and transit is at least partially what drove the requirement for all Jigsaw related passengers to carry PLBs. Remember when Jigsaw commenced, that was not a UKCS industry requirement.