The market will not stop moving due to different participants with different background and information. This is the truth and the attractiveness of forex market.
Market will only stays in a range when we are near to equilibrium. And most of the time, this period will not lasted long. When there is perceived fundamental change (in general), the market turns to the state of imbalance. Perceived is an expectation of the market and it is not the real fundamental change.
Relative movement of different pairs in T101 system allows us to find the leading pair and the market's direction. Few of the leading pairs that relatively moved the most is called tandem pairs in this system. Some trades tandem pairs as they are the strongest pairs. Some uses them as yardstick to measure the strength of market's direction.