Most golfers start with flat arms and end up with vertical arms at the top.
Starting with vertical arms and ending with flat arms at the top makes things a hell of a lot easier.
Addendum to explain above.
If you watch my plane and release by feel video it would be the arms going down, then up. That is what I don’t like. What the typical amateur does when the arms suck low in and work up and out in transition.
I just don’t like the arms working low and across thne body immediately. The hands can work in as long as the left arm works up enough.
If you’re swinging at a ball that was chest high, you wouldn’t drop the arms in the initial takeaway, then lift them back up to the initial level at address. You would try to keep them at the same level. That’s all I’m saying.