hi jeffgunter
i find if i swing at 100% i cant control the flight of the ball and i dont know if it will go right or left, if i swing at 90% i can hit a high fade 9 out of 10 time the other one 1% is still on fairway and playable, took me many years to realise its not about hitting at 100% but about control and using the club like it should and thats making sure the ball comes of the part of the club its made too and thats the sweet spot, take a ball and hold the shaft half way up and tap the ball over the face of the club, when you hit the sweet spot the club swings back of the ball with ease and not twisting, imaging what its like the other way when the club with all that force hit that little ball on that sweet spot. it really makes such a diffrence, the ball flys longer, higher and with more backspin and the back spin overpowers the side spin so flies where you want it too.
hope this helps, get into a grove where you swing within yourself and you know you always have a little extra inreserve.
bill