Was at a big convention that ended today (one where you’d assume a large percentage of attendees would have CL access) and indeed was greeted with a very long line. We were told it’d be about a 30 min wait but the line actually moved quickly and I was able to check in after 15-20 min.
There were actually plenty of single seats available so it seems that they are managing the line so as to not make it a complete zoo inside.