It sounds like such a lovely thing to be able to do with your Therapist! I know mine wouldn't plus to me the time of 50 minutes goes so quick I can't imagine us getting far. I would love to try it every so often but I also like to be in an enclosed environment when talking about deep personal things!

If I was at the stage that I didn't need to talk to my therapist about deep things and was able to use a session on going for a walk I think she would think it was time to end therapy because I must be at the stage to not need it as much.