Sorry, but 2/3 times a day training for a 4 month old is perfect.... you should really only do training in short bursts, as it is mentally tiring... so 5-10 minutes 2-3 times a day is great...
Honey doesn't have a high working drive, but we do more than 20 mins of training a week... and obedience training doens't have to be boring and stuck on a lead...
We do leg weaves, figure of eights, various tricks (bang, shut the drawer, get the post, knock over a table, hit the "that was easy button", pray etc etc), obedience stuff (heelwork, retrieves, stays, presents), agility stuff (either using equipment for jumps, weaves etc, or just following a hand guide to improve handling). And at 11 months we were doing more than we do now... every walk was a training session (loose lead walking, recall, down at a distance etc). She certainly also got plenty of time to run around, play and explore, but training really tires her out far more than just running around does... If I ever had a short lunch break at home (less than 1/2 hr) I would do a clicker training session rather than a play in the garden, as I knew she would be more settled following the brain work...
Oh... and you don't need to actually go out on shoots to do gundog training... while I think Honey is perfectly happy with the level of stimulation she gets, I have enquired about a gundog training class to be able to have more fun with her while out and about... I have no intention of ever going anywhere near a shoot (no offence to those that do, but it's just not my cup of tea) but that doesn't mean I should deny Honey the opportunity to have a go at developing the skills that are used in gundog work - even if the only practical application she gets is us being able to direct her should she lose her tennis ball in the long grass....
I don't know if anything will come of the enquiry, but at least I'm willing to look into the idea...
We also do formal obedience training and agility lessons.
Yes - at 11 months, he is at the age where he may well be at his most destructive, but unless you meet his need for mental stimulation, the destructiveness may develop into a habit which he won't grow out of.
I hope I'm wrong, I really do... Honey is my first dog, so I by no means know everything... but I think even now she would be climbing the walls if she only had 20 minutes of training a week - especially if she was running around all the time (I find she needs a little bit of brain work to calm down after a lot of running around in unstructured fun...).