Your putting routine can be variable and you can have as few as three or perhaps as many as six practice strokes each time taking a different amount of time over each putt. It really is individual and doesn't matter as long as you feel comfortable.
How long your practice routine takes depends on your ability to concentrate under pressure. Usually, under normal playing conditions, most of us feel ready after three practice strokes - three being the minimum: one looking at the hole, one looking at the ball and one looking again at the ball before looking up to determine the line.
Under pressure, however, you may need to say to yourself: "Come on, pay attention - will this stroke roll the imaginary ball at the perfect speed, just past the hole?"
Out of Bounds: "I used to be indecisive when putting, but now I'm not so sure."