I have signed up for a 10am English tour in mid Dec. I am thinking if it would be cancel due to low participation rate for that session.The tours typically book out so this shouldn't be a problem. However it seems that they will run it regardless of the number of participants, as long as you register 1 week prior to the tour.
In addition, the guided tour is of an hour duration which, isn't a bit long?
It depends on how in depth you'd like to learn about the place. The tour was pretty interesting and there was probably enough history and information that it could have taken longer. However if you feel that 1 hour is too long there is an alternate 35 min tour run twice a day but only in Japanese.