So currently we have up to 8 instructors and 8 trainees. However to have to explicitly allocate a trainee and instructor for each session, this means you waste loads of time managing the instructors/trainees, it also means that there's absolutely no point in having the ability to assign more than 2 instructors and 2 trainees to the training post (so you have the currently active instructor and trainee and the next instructor and/or trainee for a quick turn around).
What would be great is if you have a bank of instructor which bring teachable skills from which you then form a curriculum for a trainee. The training facility calls the instructors/trainees as needed or the training station becomes available. Eg. Have Ataro, Hitomi, & Vera as instructors then Lau and as a trainee. I set the curriculum as Elite Herbalist, Master Miner, Defence Boost II & Explorer Training III. Lau then has a single 37 minute training session involving all the relevant instructors, rather than the 6 sessions and having to keep on checking to see if the latest session has finished.
EDIT: put in the end of the sentence in the first paragraph