It varies......
Sorry, not very helpful I know.....the workers that will shortly be on the moors are getting three hours plus at the moment. The youngsters and oldies get less, depending on their physical and mental needs.
The dogs that just go rough shooting (mainly the oldies) will do slower, less intense exercise.
All of mine swim at least twice a week at this time of year.....am lucky to have a suitable ford/river nearby.
All the dogs, regardless of breed, are built up very SLOWLY, starting with lead walking. One hours lead walking doesn't even come close to 15 mins quartering for the HPRs, which can be required to work a beat of 200-300 yards plus. Their exercise is a mix of stamina building, training, play and socialisation. The heavier HPRs (eg GWPs, Spins etc) are taken slower than their lighter weight counterparts....eg GSPs, Vizs etc.
I never totally let mine lose fitness altogether, so out of season, they will get circa 2 x 1 hour sessions but it will be of much lower intensity.
HTH