TheScientist

I think this depends greatly on the residual effect of the practice, and what you want to get out of it. If you're working on a swing change you're probably better off forgetting about putting and short game while you bed in the swing changes you desire. Similarly if you are about to play a competition/tournament you're more than likely going to benefit from half an hour to 45 minutes on the range followed by a couple of hours of chipping and putting. As far as residual effects of practice go, the delicate touch affirmed from practicing the short game/putting is the quickest to escape us therefore we need to practice more of it directly before we play. Also getting a feel for how the greens are playing is pivotal to the scores we produce. However, I do not disagree with the findings of your study for a general upkeep of skills.

I think the best application for these is having the ability to watch your own live swing from a couple of positions at a time. Imagine if you could see a DTL view and face on view in real time. Get some proper instantaneous visual feedback going on in those practice sessions. Much much easier than using mirrors.

If you want him to improve get him to play the game Tiger used to play as a kid. He would have to play from the same tee as his dad/coach and as soon as he was in a position where he could reach the front of the green with the longest club in his bag that shot counted as his regulation approach. For example if a hole was 400 yards and he could only hit it 150 yards max he would hit it 150 down the fairway off the tee, 150 off the fairway to a position further down the fairway then play a 100 yard approach. That approach would effectively work as his 2nd shot because it was his first plausible opportunity to hit the green. Does that make sense? It's a great game, because it encourages the plotting of shots and makes the short game count.

Some golfers prefer to use set up as a 'preview feel' for their desired impact position, however it is not a fundemental requirement of a good swing. I agree that the success of any golf shot is related to impact factors alone, but there is something to be said for creating a simple and efficient golf swing from start to finish. An efficient golf swing with limited compensations is easier to control and therefore easier to repeat and, equally important, easier to make small temporary adjustments to (for hitting a high fade or a low draw when needed). For this reason it is best to improve the swing from start to finish. Anyway, with dedicated practice it does not take long to change. 1 hour every-other night in front of a mirror doing slow, deliberate swings and you'll have nailed it in a month or so, easy.

Length is down to club head speed, strike, launch angle and spin rates. A high club head speed is the operative component in hitting the ball a long way. Club head speed comes from flexibility, kinematic efficiency, and balance. Make sure power is generated from the ground up/out, maintain 'lag' as long as possible, and swing through the ball not at it. Increasing general flexibility in wrists, ankles, spine and hips helps too. Strength really has nothing to do with length off the tee, except maybe core strength. Have a look at some of the longest hitters out there, they're not all big guys.