One of the huge problems if you have a tentative attitude over shots is the variation of bad shots that can be created. So for example if you're struggling with a hook it's pretty easy to see what's happening because the ball is going to travel often a left hand side is going to really move off to the left and it's going to be hooking a long way left of the target.
What The Negative Outcomes Can Be Of A Tentative Golf Mentality (Video) - by Peter Finch