Please understand that a normal lecture is from 45 minutes to 1 hour. Optimal groupsize is 60-80 people on a normal lecture. Well over 100 people is still possible, but extra time due to groupsize will apply. For example 150 people will take roughly 1,5 - 2 hours. Groups over this size even longer. It's the hands-on that require more time.
For libraries it is smart to give free tickets, to limit groupsize.
One can also choose to have less hands-on with large groups in order to avoid the extra fee. Make contact if you have questions.
