i read romance, especially MM romance.
I have been to larger signings in the Europe, a mix of MM MF. There you pay one amount, you queue to get in (but it's quite fun, plenty of time to chat with others) and how long you spend with an author depends a lot. Very high-sought after ones - you really just spend 15 seconds it seems. I had one where Julia Quinn attended when Bridgerton was just out the year before, it was mayhem but she just signed a book, said "nice to meet you" and off you go to make space for the next one.
Other authors are happy to talk, about their lives, books, travel.
These signings are just one day, some with smaller venues have 2 days with different authors on different days.
There are sometimes organised meets the day before but it's not often. There is a huge Facbook community which often organises stuff themselves.
Pure MM/queer lit signings - smaller, 50, not 300 authors. There is often a meet the night before and an organised party the evening of the signings. I spent the whole 6-7 hours just chatting to the authors and also to plenty of other readers I met on other occasions, The authors are mainly indie, with a large social media presence and it's a nice community.
In the US there are some signing where they offer tickets which include special events with authors, meals, activities and after-parties. There are panels you can attend as a reader. There is even now a queer lit cruise one, stuck on the ocean for 3 days together.