In Berlin we had 80 people attending the conference. The room was nice and big with possible space for over 100 attendees. We planned last year for Munich with 2 conference rooms. Just in case we got more people and would like to have two tracks. Six months before the event, we cancelled the second room as we only had around 30 people on the list that early. It doesn't make sense to have two tracks and only 20 people in each room.
For our Cologne event we planned a nicer conference with a ballroom and a lot of space to host even over 100 people. We started planning the schedule for two tracks and invited speakers.
Sadly the attendee numbers don't add up as much this year. We are just about 50 people and far away to fill two rooms for running with two tracks. The contract with the hotel allows to cancel 4 months in advance and we are have reduced to half of the space. We informed the speakers and attendees that we move all sessions in one room and reduce sessions to about 45 minutes each. The improvement for you is that you can now listen to all sessions. We still plan to record them and if you have to make a call or talk to someone in the foyer while a session, you can later watch it.
If you like to help the conference planner, please commit early for the conference and sign-up as early as you can. Don't wait for the last months as the conference size is reduced or enlarged months before the conference takes place. Such a conference is usually planned a year in advanced and adjusted about 4 to 6 months before to make sure we don't have too many empty seats.