You aren't always able to play in the zone. You aren't always able to just let the swing operate without conscious control--sometimes a great deal of conscious control. Bobby Jones almost always relied on one or two swing thoughts to keep his swing under control. They weren't always the same ones, but he relied on them to produce decent results when he might not be at his best. He advised us not to believe that any of the pros played golf unconsciously. He assured us that all the top players used swing thoughts.
The sweet-swinging Sam Snead used swing thoughts or triggers to keep his smooth, natural-looking swing in the proper groove. Jack Nicklaus used them too. We need them. We can't just rely on the fact that our swing will stay in the groove. We need to keep it there consciously by finding key swing thoughts that work. In his book, Golf My Way, Jack wrote the following under the heading "How Many Swing Thoughts?":
"The time to focus your mind on key swing thoughts is as you settle into your final address position.
When my concentration is good I can focus my attention at address on five or six different things I want to do in the swing, and then actually do most of them. For example, in the 1972 U.S. Open at Pebble Beach, where I was playing many left-to-right shots, at address on any particular shot I might simultaneously be thinking of making a specific type of forward press; keeping my head in a certain position on the backswing; keeping my hands low going back; making a very slow and deliberate takeaway; keeping the back of my left wrist to the target; making a full backswing; working my legs in a particular manner; keeping my head back during the forward swing. When I am not concentrating well, however, I find I can focus attention at address on only one or two swing keys.
How many you can focus on will depend on your levels of skill and concentration. On average, I'd say that two is about the handicap golfer's limit, and that he'd be better off most of the time with only one key swing thought.
I must stress, however, that no matter how many things you think about at address, you are, so to speak, merely programming the computer. Once you throw the switch, the computer must take over. The golf swing happens far too fast for you to consciously direct your muscles. Frequently I can make very minor adjustments in midswing, but they are always instinctive, never conscious."
So, there you have it. When he won at Pebble Beach in '72, Jack had a bunch of swing thoughts. It's interesting that he felt the better he was concentrating, the more he could have. Kind of flies in the face of the idea of playing golf subconsciously, doesn't it? Oh, and notice that one of the key thoughts was keeping the back of his left hand to the target? That's Top Hand Golf.