Catering schedules reflect scheduled routes and the stocking is planned in advance. Whether the route has been operating for years or only a week does not matter because the requirements will have been provided in advance. The caterer has its standing orders. Air Canada doesn't make meal selections at the last minute substituting pretzels for an entree. Rather it is the caterer that does that. Air Canada provides its stocking requirements and it is up to the caterer to fulfill the order and to deliver that order to the right aircraft on time.
How many times have we been on flights when the caterer doesn't provide sufficient wine or leaves off the snack bags or part of an order? The failure to deliver the order as agreed upon ontime is the responsibility of the caterering contractor. Where a miscommunication can occur is when gates change for the aircraft, but these changes are supposedly updated in real time. If pax know which gate an aircraft will be at, then the caterer knows too.
We all lament about the airline monopoly in Canada. How about the catering monopoly? As a tangent, Air Canada is to be commended for giving Newrest a try out of YUL. Since, the change over, on my limited number of flights, my experience has been positive.