Yes, this is very interesting.
Many people ask me when they learn that I have a young Labrador if I have to exercise her for miles each day, and assume that I spend hours doing just that very thing. Well no, I don't.
I do a lot of training during our walks, anything from heel, sit/wait to retrieving, and all sorts of games. On the days that I work, she may just get a lead walk one end and a short off lead walk the other end of the day. I always make sure she then gets a "walk" of an hour to an hour and a half at least 2 days a week, but other days we so 20-30 minutes training, maybe twice a day. I'm finding that now she is 3 she really enjoys engaging in activity sessions, rather than just me walking and her bumbling along. Whilst sometimes she's been a real live wire out and about,and loves to hunt, at home she's really relaxed and chilled. So I think I've got the mix right, for her