And, Tiger's been in the gym. Beyond 6 reps strength begins to become muscular stamina. Muscle size, or cross-sectional area tends to be an important aspect of strength development. Strength is a prerequisite to power, and a periodized training program takes this into account in the weeks and months before a cycle of power conditioning begins. Strength training, although an end in itself is a platform from which to step up to power.
Power training is peaking and is performed in relatively short cycles, prior to an important event.
When these cycles are extended then performance declines. Strength training though, because it doesn't tax the body quite as intensely can be utilized longer. Strength benefits can be realized from lesser loads, too with as many as 10 reps. And, depending on the athlete, perhaps someone who's well out of shape even higher reps. But the point is, there's enough variation within a strength phase that progress can be maintained for quite a while.