And you'll find examples of successful touring pros who use each one. In The Golfing Machine (TGM) parlance, the active straightening of the right arm (primarily driven by the right tricep) is described as using Power Accumulator (PA) #1 and is heavily associated with the "hitter" swing style.
Regardless of what is taught, used, or believed, there seems to be one universal truth, at least visually, with regard to the right arm in the full golf swing when we examine the swings of great players: The right arm folds in two places--the elbow and wrist--in the backswing, and the right arm gradually unfolds in the downswing, reaching it's fully extended, released position (right wrist and elbow straight) a foot or so past impact. The left wrist never breaks down or bends backwards (i.e., flips). The right arm straightening can be passive for swingers or active for hitters.
The first element of properly using PA #1 involves keeping the elbow and wrist of the right arm bent for as long as possible coming down. Ernie Els describes this as "keeping the box." The right elbow should still be slightly bent at impact, reaching a fully extended, released position only a foot or so past impact, with the right wrist still bent backwards (even just after impact). Doing both automatically extends the left arm fully and keeps the left wrist flat through impact. Pressure should be felt in the first phalanx or base knuckle of the right index finger from the top and through impact. In a sense, that phalanx or inside base knuckle of the right index finger can and should serve as a guide to the club face position throughout the swing. The right hand thumb and index finger should be completely loose around the club handle; you can even take them off! Only that phalanx or base knuckle is important.
If the right wrist straightens in a way that causes the left wrist to bend backward at impact, this creates a "flipping" motion and the club head will pass the hands (lag is lost and the effective loft of the club is increased). Instead of "flipping" or swatting at the ball with the right wrist (behaving as if it was merely a door closing along its vertical axis), the right wrist should only straighten WELL AFTER impact with the right palm rotated slightly downward through impact.
This reflects the TGM description of hitting down on the ball with the right palm and actively straightening the right elbow, feeling pressure in the base joint of the first finger of the right hand (Pressure Point #3) and pressure on top of the left thumb (Pressure Point #1) due to pushing on the left hand with the right. This creates a feeling of pushing down and out on the shaft with the right palm, and results in a flexed shaft due to the compression against the ground; a divot is taken well in front of the ball. The ball is often described as being powerfully "pinched" off the ground or "compressed against the ground."
Use this one swing thought: Aim to fully, dynamically straighten the right elbow a foot or so past the ball with your irons. Straighten it down, forward, and out. You can use this method to hit the driver; simply use less downward extension. Instead, extend so that the right forearm is more level with the ground coming into the ball. Straighten it out to the right slightly for a draw and out to the left slightly for a fade.
The best way to describe [Kenny Perry's] right arm on the downswing is that it is "pushing down and out." Pushing down allows the right arm to actively straighten while maintaining the bend in the right wrist. This feeling is no different than if you were to try to push something into the ground with your right arm.
Maintaining the bend in the right wrist is a fundamental you see in a good swing. It allows the clubshaft to return forward at impact, resulting in a clubhead that is descending and accelerating through the impact zone.
"In essence, bending and straightening the Right Elbow will raise and lower the left arm and/or cock and uncock the left wrist without bending, flattening, or cocking the right wrist. Right elbow action either powers and/or controls all three elements of the Three Dimensional Impact, (downward, outward, and forward)." ~ Homer Kelley
In a golf swing (whether one is a hitter or a swinger), the right wrist is always bent back and the right wrist never bends forward (palmar flexes) at any time point during the downswing - because it would cause the left wrist to bend forward (flip).
Whether one is a hitter or a swinger, the clubhead should never flip past the hands while the clubhead is moving through the pre-impact zone. The clubhead should always be lagging behind the hands during the entire downswing, which means that the right wrist is always bent back.
[A] hitter applies an active push-force at pressure point #3 by actively extending the right elbow during the downswing - as the right elbow actively straightens it applies an active push-force via the bent right wrist to pressure point #3.
PA#1 is only actively released in a hitter's swing action - when the right triceps muscle actively contracts with a large amount of isotonic force, thereby straightening the right arm in a straight line thrust action that thrusts the right forearm downplane and drives PP#1 [the left thumb]/PP#3 towards the ball (or towards a desired aiming point in the vicinity of the ball).
The release of PA#1 is due to a very active triceps muscle contraction that actively straightens the right elbow in a forceful thrust action that pushes the right forearm and bent right wrist towards their impact fix position.
Throw the club through the ball with your right hand. As Jack Nicklaus said, you can hit as hard as you want with the right hand as long as the lower body is leading.
That right hand does not stay as loose as it does on your backswing. You take it back loose, your hands are nice and flexible. But when you hit that ball, you’re adding power to it and you’re increasing your pressure all the way through impact.