Just because the ball has already left the clubface it doesn't mean it's not important. On the contrary. If you just observed a person's follow-through you could (in the majority) tell whether that person is a good golfer or not, and here's an example of this:

Hank Kuehne (PGA Tour Player)                              25 Handicapper

Very rarely do you see someone with a good follow-through who has poor mechanics before that. So does that mean you should try to have a good follow-through?

Not necessarily....but practicing things to improve your follow-through will have a good overall affect on your swing.

Why?

Because to get into good follow-through positions you'll have to do things prior to the follow-through that will help to improve your swing. Now having said that, unlike everything I've discussed previously, the follow-through is one area that I'm more relaxed about what should happen. Because this is one area that allows our differences to shine.

All golfers don't need to look the same at the end of the swing because all of our swings have different characteristics, i.e. one person will be a power player, another person will have a more conservative, more mechanical swing etc.

The follow-through is where a person is more free to do what comes naturally to them. However, there are certain things that you should be doing in the follow-through and we're going to start looking at what some of those things are now.

As I said a minute ago, the follow-through includes everything that happens after the ball is hit until the finish of the swing. And there's something that happens in the follow-through that should happen at no other point prior to that.

What I'm referring to is that both of your arms should be straight just after impact.

Important Note: At no other point previously in your setup or swing should both of your arms be straight.

Now when the club is in a position where it's parallel with the ground in the follow-through the clubface should be vertical or straight up and down like this...

At this point in the follow-through the clubface should be vertical or straight up and down.

Also, both of your arms should be straight and extended to the target. And your head should be in a similar position to what it was at setup. Your hips should be open and most of your weight should be on your left side.

All right, that's the some important parts of the follow-through covered. But now I'm going to go into more detail on the release because I know that getting to a position like the one picture above, i.e. the clubface being vertical at this position in the follow-through, can be tough for a lot of golfers. That's why I give my students the best drills I've found to fix this problem.

But most golfers that get in bad follow-through positions do so due to a lack of lower body use, coupled with a lack of right sided power/dominance in the downswing. Now the lack of power/dominance from the right side in many golfers swings is probably a result of golfers so often hearing that we need to quieten down our right side.

However, this is just bad advice and sadly ruins many golfer's swings. But the great golfers know this isn't true and that's why you get golfers like Ben Hogan saying...

                                        "As far as applying power goes, I wish that I had three right hands!"

Ben Hogan                                              

So let's clear this up once and for all.

The right side is the power side in the golf swing and you want to apply as much power as you can with this side. The left side is simply there to support and help guide the swing.

Now when I talk about your right side I'm not simply referring to just your right hand. I'm referring to your entire right side, i.e. hand, arm, shoulder etc. And when you follow-through your right side should be much more dominant than your left side. Your left side should be trying to get out of the way of your right side coming through.

Also when you follow-through you want your right side to actually feel like it is going down and around. The only way of doing this naturally is to swivel your head to the left once you've made contact with the ball. Look at that Hank Kuehne picture above to see what I'm talking about.

By swiveling your head at impact and following the flight of the ball it allows you to swing under with your right side -- naturally. If you try to keep your head still after impact you'll find it very hard to get your right side working under and this will cost you a lot of power.

In short, a fixed head will restrict your swing and cost you distance.