I never had a T cancelling last minute. I selected "I prefer a week or so when possible", simply for planning my life. I am quite adaptable and only care much about last minute changes when it is an important work project or a more extensive activity, but have a generally busy schedule and I adjusted in to incorporate therapy. If I know cancellations in advance, I can plan other things, including just some extra rest at home. In a great deal of time when I was in therapy, I also prepared for sessions a lot mentally and would not have enjoyed that being disrupted, although not a big deal.

I definitely would not want to talk with the T about cancellations in length, definitely would not want to spend a session with that. I think that sometimes some Ts overinterpret these things and project significance into them where there is none. For example, if someone cancels on me, I don't sense it as a personal rejection or a blip on our relationship, just maybe some annoyance about my schedule and projects being messed up. And if it is frequent, a lack of reliability, which is not very desirable in a professional.