Interesting topic, and relevant to my swing (in the “opposite” direction).

One of my problems is not turning enough in the backswing (which also doesn’t let me get the wrists hunted properly), and @iacas has always simply said “finish turning” (shoulders).

No mention of the shaft getting to parallel. 

The second comment in response to the original tweet says a lot also, showing that he read the tweet and still doesn't understand that a full swing =/= going to parallel

I can relate to this, one of the things my instructor worked with me on (and is still a work in progress) is stopping my arms when my turn was done. I had a bad habit of completing the shoulder turn, but the hands and arms would continue to go up and back well after my turn was completed. When I feel like my swing length looks like Finau's, my strike is much more solid and consistent, especially with the irons.

I don't watch much golf anymore but I don't really see the pros getting to shaft parallel.  I've never consciously tried to and I think I only do with my driver 

6 hours ago, TN94z said:

It is funny that this post came up during this time. In my last lesson, we worked on shortening my swing. We had tired this prior to last week because I felt as though it was too long and the way I was getting there is what brought my troubles into the picture. We finally figured out a feel that shortens it quite a bit 

What was the feel that worked for you?

6 hours ago, TN94z said:

It was basically feeling like I was driving my right leg (right handed) into the ground on my back swing and keeping some flex instead of extending it to almost lockout like I was previously doing. This physically limits me to a shorter back swing. I am just not flexible enough to have this move and swing any further. But "for me" this is perfect because it allows my shaft/club face/arm positioning to get in a much better position. The other feel that I do not think about, but it happens naturally, is that it almost feels like my legs move apart rather than my lead knee moving towards the trail leg in my back swing. My first fear was that the shorter back swing would hurt my distance but the better contact that I am making now easily matches the distance with a much better ball flight. This lower body change also makes hitting the correct swing path easier to achieve with less manipulation so it will make the other changes that need to happen in my swing much easier to reach. Obviously, this is what has been working for me and the problem I was having in my swing. I am a big feel player so it is hard for me to make a swing change if I cannot find a specific feeling that I can recognize that puts me into the right position. 

So are you saying this lower body restriction via the right knee prevents you from letting the arms cross the chest too much? Were your shoulders turning more than 90 degrees?

36 minutes ago, TN94z said:

No. The lower body being in this position stops my trail leg from locking out, my lead leg from sliding towards my trail leg, and my arm swing from being too long which gets to a point that the lead arm collapses. It also limits the amount of hip turn I can have. I was trying too hard to get a lot of hip turn at the expense of swing path. I have always tried to shorten my swing by "thinking" about a shorter swing but it just never worked consistently. My shoulders may have been a little greater than 90.

My teacher told me that I was exaggerating the hip turn in my back swing too much. I never really realized how far I was trying to turn my hips until we put the alignment rod in my belt loops. The arms are moving the same as before. My full swing point is just much earlier than it was before. For me, this has led to less manipulation and having a huge "timing" factor in my swing. I feel in much more control of the swing now. I may not be explaining this the best.. I feel like I am working more into my trail knee than around it. Kinda like it is now using the ground for power instead of me trying to " arm swing" faster for power...if that makes any sense.

Oh ok, so it sounds like it was never an issue of your arms traveling too far or continuing to travel after the shoulders have completed their turn - which is definitely an issue for me. I'm flexible and am only now beginning to understand that keeping the arms more centered to my torso is important, and not to let my arms cross my chest like Gumby even tho the lead arm is completely straight

Thinking L to L helps me sync my swing and the ball flight is much better.  I too have a backswing sooo long that it sways me off the ball.  The L-2-L drill and thinking slow backswing like Matsuyama is helping.