I think that depending on the distance from the hole, lie, and confidence. As you approach the ball you can get your understanding for what club to use and whether you need to club up or down with the conditions (which should take probably 10 seconds minimum). Then you line up or take practice swings behind the ball, or however you do (which should take 10 second or so), then you take your shot.
You shouldn't think too much on how you swing if you have all the fundamentals down, if you struggle with getting you body rotating or your club all the way through the ball. When you take your p