The longer it stays sideways, the more it will rise.

"How long is horizontal and how high is vertical?" When the market is moving sideways, the operators are actually busy accumulating positions. The more they accumulate, the stronger the subsequent rise will be. This is what is called "main force building a position"; you might think the market is quiet, but in reality, a significant rise is brewing.

A sudden drop during a sideways market is often just a washout; after the drop, there must be a rise. Conversely, if there's a sudden rise, don't be too happy too soon, as it may just be a trap to lure in buyers. The market makers are washing out the weak hands before the real trend starts. Remember, after the "washout" is done, the real opportunity will come.