Staff numbers, Fury has maybe 3 in the station doing loading including the batcher (I've not seen more that four this year), Spinball had six on an off-peak day doing the same job.
Plus Chessington don't allow people to go into the station now until the existing riders have cleared the exit gate and it closed, many a time earlier this year were we told to wait at the scales until the people getting off the ride had collected their bags and cleared the gate, made even worse when the ride op then needs to do a height check before letting you on (instead of doing it while you waited in the queue or simply using the common sense of kid is taller than fence so doesn't need checking), my son is 1.6 but they still insisted on checking his height.
All this means they then have to stop the car in the station and wait for you to board, causing the existing cars to stack on the brake run.
It may have improved since our last visit but double that with a generally very different attitude from staff down south and it's easy to see how operations are so different.