I certainly appreciate the point you're making, and I agree with you that the guides are a very professional group of people who are very well-versed in the history of the buildings. They offer a great service to visitors and help enhance their experience of visiting Ottawa and Parliament Hill.
As to the management of the tours, that is not something the Board of Internal Economy would oversee. That's done out of the library, which is its own entity. They have their own challenges in meeting certain strategic operating review targets.
I don't want to venture a guess on what would be causing the backlog you're describing. It could be a simple function of not enough hours in the day, or of having a certain limit on how many people can be physically accommodated in the hallways at the same time, or of the number of guides they have.
I can certainly bring that up with the parliamentary librarian.