There's no reason why a reasonable golfer should take more than three to get down from 150 yards. If you spend most of your practice time hitting a 7-, 6- or 5-iron whichever you use for a 150-yard shot, you should hit the middle of the green and now and again sometimes the ball will roll up close to the hole and make you look good.
The golden rules of when you should chip, pitch or when you should putt are governed predominantly by the lie. If it's good and it's uphill, soft green and perhaps an obstacle in the way you'll probably want to pitch the ball. Poor lie, hard green, downhill stance, windy day and under stress will point you towards considering a chip. Good lie, smooth flattish surface -- using your putter will get the ball closer to the hole nine times out of ten.
Use the full length of the club and grip down when hitting a pitch shot with the wedges now available. Gripping down on any wedge is conducive to making a chili-dip, which comes from dropping your head and bending your left arm at impact, causing you to hit behind the ball or making a top. Never allow the clubhead to pass your hands on the follow through of any chip or short pitch. Playing the ball back in your stance will help if you have a tight lie, try closing the blade until it is square to the line and the bounce of the blade does not touch the ground. Adjust your stance forward to compensate for direction. Put slightly more weight on the left foot and strike the ball and the ground at the same time on the downswing.
Out of Bounds: Nothing of what happens when you strike a golf ball should be by chance ... if you're relying on this to get you around with a good score -- God help you!