I think they are covering all bases in case they do not get any applications for the whole period. In these cases I think sitters that apply for all dates will go to the front of the queue
The Rideau canal does not open for skating until January unless the weather is very cold for several days. If I recalled only once the canal was opened for skating in Dec during the last 20 years. We live in the suburb has lots of restaurants, groceries stores including public transportation all within walking distance or short drives.
What a wonderful responses from the community. It really gave us the confidence to consider this option.