Three Wrongs And A Right
I'm an advocate of a big golf swing. Go ahead and take the club back past parallel if you want. But do it right. Be aware that there are three bad ways and one good way to make a big swing.
Bad way number one is by loosening your grip at the end of the backswing, and letting the clubhead flop toward the ground. Unless you can perform a miracle and regrip perfectly before impact, this loose grip will produce loose shots. Faulty method number two - probably the most common error - is overbending the left elbow. This adds a hinge to the swing, a hinge that rarely works smoothly. And the third mistake is to toe-dance at the top of your swing, raising up onto the toe of your left foot as you lurch for the sky. From that position, there is no safe return.
The proper way to make a big backswing is with a big turn of the hips and shoulders. It's okay to have a little lift in your left heel, and it's okay to have a bit of flex in your elbow too. But don't overdo either, and by all means keep a firm hold on the club, particularly in the last three fingers of your left hand. But the key is to turn your hips and shoulders so that at the fullest extent of the backswing your back faces your target. If you can't make this 90-degree-plus turn naturally, then try some flexibility exercises - but don't 'cheat' your way to a big swing, as it will only bring big trouble.