ICR Excursions

We are hoping to book a couple of excursions during our stay. I see that a few of them state the day(s) of the excursions, yet some dont.... on the ones that dont, do I assume that it is arranged if there is enough demand?
The reason for asking is that in the past we have been disappointed because there was not enough interest.
The reason for asking is that in the past we have been disappointed because there was not enough interest.