Yes a big consumer of time is refuelling and baggage. In a serious emergency the latter is surely dispensed with, the former will depend on the range etc, but it might be possible to refuel at a nearby installation once the pax are off the rig.
Lifejackets? Well if the rig was on fire, I think life jackets can be dispensed with, although no doubt there will be some jobsworth who says "rules is rules" whilst the flesh is charring!
For a normal turnaround, as TM says 20 mins is a good figure, so from that you can subtract elements to whatever the degree of urgency dictates.