Not an expert but your question intrigued me - I found a document (https://pancanal.com/wp-content/uploads/2021/08/N07-2021.pdf https://pancanal.com/wp-content/

Not an expert but your question intrigued me - I found a document (https://pancanal.com/wp-content/uploads/2021/08/N07-2021.pdf https://pancanal.com/wp-content/uploads/2021/08/N07-2021.pdf) which has a lot of info about how transits work. It does look like commercial passenger vessels get special treatment: they're exempt from a requirement to arrive the day before their booking, and they're allowed to book transits up to 730 days in advance, and on the other hand required to book no less than 366 days in advance. Other vessels wanting to transit the Panamax locks in the normal fashion have booking available on various schedules between as much as a year in advance and as little as 2 days notice, so queuing is inevitable. Essentially the uniquely predictable schedules of cruise ships mean they can be handled separately from the often ad hoc trampiness of cargo arrivals!