We've largely been following this "rule" with our pup (approaching 5 months now). It serves as a nice guide to follow and makes us reign the walks in when we want to go further. We occasionally go over a bit but if so then we limit, for example, the evening walk to a quick nip out for the toilet.
However, we wondered where this "rule" comes from. It's obviously a very general rule which seems to be applied to every breed without much discrimination.
Online forums seem to be an echo chamber of disagreement on whether the "rule" (which is just a guide) means on lead walking, some think it means you can do 1 walk a day whilst others say 2. Some think you can do unlimited off-lead walking.
Is there any scientific basis for this "rule" or is it just good practice?
Basically we're happy to keep following it as our pup is a Cocker Spaniel whom often have joint troubles in later life, but it would be interesting to read any studies all the same. Does (for example) doubling the daily limit every few weeks (e.g. going for an hour when he's 6 months) increase the risk of joint troubles. I guess there's not much research into it, but if anyone knows of any it would be great to read.