Yes. Buses are great at scaling up (much better than trains) for special events. They are bad at scaling down. A bus with less than a van-full of passengers is a huge waste of resources and roads space. In times of low utilization, buses shouldn't be blindly running their routes.
A bus route needs to run reliably all the time so that people can depend on it. There is little difference in the cost of running a large vs small bus so running a large bus all the time is almost always the best answer. And cities around the world discover that running reliable all day service means that you end up with more than enough passengers all day as to be worth it.