
Retrievers are bred, primarily, for picking up. If you've seen a dog picking up, it involves a lot of sitting and doing nothing, interspersed with possibly retrieving a bird (depending on how good a shot you're stood behind). So actually, working retrievers, although they do need some stimulation, also need to be steady and sit still for long periods. I have a working bred FCR who is just like this. I also have dual purpose bred Labrador retrievers, and the girl I work would be bored out of her skull picking up, so I take her beating instead, which is just as enjoyable and much warmer as you're moving more. The other thing to consider is that on a shoot day, dogs get up close and personal with all other dogs and people, so they need to have a good temperament.
Either way, a well bred retriever, whether working, show or inbetween, should have the ability to settle down. It never ceases to amaze me when people say their dogs couldn't possibly go without walking for a day. I had mild heat exhaustion last weekend, and didn't walk my dogs for two days, they were fine, they just got told to settle (I live on my own). It does make me wonder how some owners of dogs keep them calm when they need to for health reasons.