I know he needs more attention, but when he is consistently getting it - his behavior isn't any better. It actually tends to be a little worse. Don't get me wrong, whenever I can, we go to the open area to throw sticks/let him run, etc (about to right now), but then once we get home, he is so wired for like an hour, that he is biting my feet anytime I try to walk, jumping up, grabbing my hand etc. At the park, he gets so tired that he just lies down, so it isn't like I'm not running out his energy. We usually go for a walk after the park too. But to be realistic, I cannot do it everyday (he obviously gets walks everyday & gets to run around in the yard though)
What about more structured exercise? Running around mindlessly/playing fetch does little to nothing for my dogs. They are still physically set to go and mentally it did nothing besides get them amped up.
But biking? Hiking (on a long line for a dog with unpredictable temperament)? That type of stuff takes it out of them physically and mentally. Short training sessions that are very mentally taxing such as shaping things and working on self control/impulse control. Even flirt pole with impulse control and training thrown in.
That might do more for him on the exercise front than any game of fetch or just free running around a park. And, if you plan ahead I think it would take less of your time overall.