The flex rating you use will depend on the type of swing you have. For example, beginners and those with less powerful swings tend to use an axle with greater flexibility to push the ball more. On the other hand, if a player has a high and powerful rotational speed, they will need a stiffer shaft with less flexion. For medium to high handicap players (with a slower rotational speed), you'll want a lighter axle and, probably, regular flexion.
Add the driver heads that fit and the fact that individual axles can be cut from the end of the tip to alter stiffness, and it seems paralyzing for the solitary golf consumer to even start the journey to find the right one. As Briand says, a longer shaft will cause a less consistent blow to the face and the golfer will tend to hit the ball closer to the heel. When you love the driveshaft, try playing with the same model but with different weights on your street woods and hybrids. Here's a general breakdown to give you an idea of which shaft flexion is right for rotational speeds.
The Fujikura Ventus, which was the most played on the PGA Tour, is available in 23 versions on its website. Placing a golfer on the exact right axis for them via the Internet is a difficult task, if not impossible. As I mentioned, one of the biggest mistakes that many fans make with iron is touching axles that are too heavy. If you choose the wrong flexion, the club head won't hit the ball directly, affecting your distance and the trajectory of the golf ball.
An axle that is too stiff can push the ball to the next street, while an overly flexible shaft can cause a fall or an unpleasant hook. On the other hand, as you age and lose rotational speed, you may want to opt for a lighter axle with more flexibility. It is important to note that variations in shaft length and inclination will affect the designed bending point of the shaft. Fortunately, golf club manufacturers have been offering high-end axles in recent years, so be sure to check what is an improved option and what isn't.
But no matter how detailed the analysis is, the right axis usually comes down to the blow and all the peculiarities that entail. That's why it's best to get in shape on the driveshaft under the supervision of a professional fitter. Since their golf swing is more developed and is more consistent, they have certain requirements that most players don't worry about.