The 5 minute rule is supposed to be used as guidance. I think it is a useful tool to have in mind when exercising young puppies. I don't think you need to stick to it rigorously but at the same time if the 5 minute rule suggests 20 mins every day for your puppy and you are doing 60 mins every day then that isn't really sensible, however the odd 60 minute walk probably won't do any harm. With Wcs it's not just about exercising the physical energy but mental as well. When mine was a puppy we did a lot of hunting in the garden and house for treats, practising recall and stopping on command in the garden, retrieving of toys etc. If you combine a few of these sessions in the day, along with a reasonable walk, then that should really be enough. The rest of the time your puppy/dog should learn to settle themselves and chill out. As I have said before, my Wcs has a decent walk once a day where she is on full, hyper mode and a we might do a bit of play in the garden but for the rest of the day she sleeps.