Here is an example of how I used Express Transportation during one of the days I visited. I should disclose that I was by myself, it was day 3 of my trip, and I wasn't planning on doing many rides during the first part of my day. My last stop was going to be Magic Kingdom where I was going to end my day and close out the Park.
On the Saturday before Easter, I made it to all four Parks in six hours, and only went through Security once. The first Park that I visited would be the only place that I had to go through Security since I would have to go through its main entrance.
I started my day at around 900 at Animal Kingdom. I wanted to walk through some of the trails in the morning and take some photos of the Tree of Life. It was a really quick trip so I was ready to leave by about 10. Before I checked in, I had gotten a cup of coffee and a pastry that I could munch on while I waited to be escorted to the Express Transportation bus.
This particular bus trip had the most people that I had ridden with while trying out this service. There were probably about a little over dozen people that boarded a bus to go to Hollywood Studios but it was still easy to get a seat. Plenty of room for those families who had strollers, too.
My second stop was Hollywood Studios. I managed to squeeze in a visit to see the new BB8 Meet & Greet, watch One's Man's Dream, and watch the Stormtroopers March, twice. I even waited to see the Star Wars stage show and had some time to shop. My next stop and third Park hop was Epcot.
I got to Epcot with the intention seeing the rest the Flower & Garden Festival that I had missed on my first day. When I got to Epcot, I had time to go through stand-by for Spaceship Earth. I also waited in line for a photo-op with Baymax. Than I made way to World Showcase to take more photos of the character topiaries and try a out a couple more of the yummy food booths.
After a couple hours, I made way back to the Express Transportation to catch a bus to the Magic Kingdom. I had dinner reservations for 530 pm at the Skipper Catina. I was meeting a friend so I didn't want to be late. This was my fourth and final Park visit for the day. I spent the evening at Magic Kingdom since it was open until midnight.
Here is a summary of my Park Hopping timeline:
Entry to Animal Kingdom main entrance & Security, 9am
1st Park Hop, 10:10 am - Animal Kingdom to Hollywood Studios (20 minute ride)
2nd Park Hop, 1::30 pm - Hollywood Studios to EPCOT (less than 15 minutes)
3rd Park Hop, 4:10 pm - EPCOT to Magic Kingdom (about 10 minutes)