Sort of depends on how you define cancel. Last year, I didn't really ever cancel--there were several times I moved my weekly standing appointment to a different day because of work or vacation or other circumstances, but there weren't any weeks we didn't meet on my account. There was even a time I had therapy on a Monday, left on a 10 day trip that evening, came back the following week on Thursday night, and then had therapy Friday morning!

This year, I have standing appointments twice a week, so if you define a cancellation as a week when we meet less than 2x due to my schedule/availability, then cancellations are much more common--there have been at least 2 weeks when we only had one session because I was traveling, and there will probably be at least 4 more this year.