There is no getting around this.
* Time required for old customers to unload: constant and a wash.
* Time required for new customers to load: constant and a wash.
* Time required to move the train from unloading to loading station: only applicable to separate stations, so this makes this method take longer.
Period. End of story. If you want to increase your throughput, add more cars to your trains and/or decrease the interval between train departures. NOTHING else increases throughput, no matter how you arrange the stations.
Bullethead,
Having worked in the theme park industry and on station design I can tell you that you're actually dead wrong here.
To increase the guest throughput you have to take a look at the total time it takes a vehicle to leave a station - not the time it takes for the same vehicle to leave the station, but basically the overall station interval. Usually, this equation is equivalent to
Track time + unload time + Load Time = TOTAL CYCLE
but there's ways around that.
We'll take 3 examples:
1) Disneyland's Fantasyland Style Rides (Pinocchio, Peter Pan, Snow White's Scary Adventure, and Mister Toad's Wild Ride)
Disneyland utilizes separate unloading/loading stations on these attractions, and by putting a number of cars in between, creates a significant buffer. By making the unload and loading at different locations with a number of cars in between, the station can increase it's throughput. Case in point, if a passenger takes a really long time to unload at the exit of the attraction two or three cars can still load up and enter the attraction without causing a station slow down. This is more efficient, and this station technique is still utilized today (see Winnie the Pooh at Disneyland, or Goofy's Sky School).
This station design changes the total time to LOAD/UNLOAD (whichever is longer) +TRACK TIME = Total Time
2) Disneyland's Dual Station rides (Indiana Jones, California Screamin, or Bug Thunder Mountain Railroad)
Again, here a car can be cycling passengers while the other station is already up and ready to go. In a worst case scenario, one side of the station can again be backed up due to slow passengers while the other station continues loading passengers endlessly. Theoretically, if enough stations were provided side by side, you could always have a train ready to leave the station while another one is heading in - this is the <i>best</i> way to build stations as it reduces your total time the most:
Ideally, TRACK TIME = TOTAL TIME
3) Simultaneous train loading (Pirates of the Caribbean, Splash Mountain, Autopia)
The idea here is similar but more space efficient that the previous two. Basically, since loading and unloading takes so long on these attractions (longer than the block spacing requires) - we batch load/unload reducing the the overall amount of time that it takes for trains to leave the station. This then changes the cycle time to
1/2 LOAD+1/2 UNLOAD + TRACK TIME = TOTAL TIME
Essentially using parallel or sequenced loading/unloading can greatly increase the throughput of your attraction. Yes, additional trains, block breaks, and space would be required, but you will see actual gains on your guest throughput and increase your THRC.