We have used Park n Go at least a dozen times. They run a very efficient operation. They have plenty of vans and lots of staff. When going to the ship, they wait for the vans to fill up but that is usually 5 minutes or less. I wouldn’t bother dropping off luggage at the port.
When picking us off the ship, we have sometimes left immediately with just us on the van as there were shuttles right behind us. They take you right to your car and will even load your car if you want. We tip the driver both coming and going.
in all of our trips, we went straight to our ship, no multiple stops.
If you pay in advance, the cost is way less than the port and there is minimal walking involved.