What it actually decides.
What makes a session general is attendance rather than size. Ninety people at an all-hands in a hotel ballroom are in a general session; four hundred in a track room with two other tracks running are in a breakout. The test is whether anything else is scheduled against it, and the answer changes what the room has to do.
Because everyone is in there at the same time, the general session sets the peak for everything counted per head. Seats, exit capacity, assistive listening receivers, radio microphone channels and camera positions all reach their maximum in that one room on that one morning. A conference equipment list is usually sized by this session and then reused, at a smaller count, everywhere else.
It is also the only part of a conference that gets rehearsed, so the hall is occupied twice. Once for the show, and once — the evening before, or at six in the morning — for the cue-to-cue and the speaker walk-throughs. A room contracted for the programme hours alone leaves no window for that, and the gap tends to surface after the contract is signed.
The predictable failure is content. Slides, videos and running-order changes arrive in the last forty-eight hours, and somebody has to collect them, version them and build them into one playback order before doors. The room can be perfect and the show still stalls on a deck that reached the operator during the walk-in.