The problem with declines is that they can follow a lot more paths, because there are numerous corrective patterns. At the start of a bear market, all you have are hints. You have little certainty about which one of the shapes is going to take place. All you can say is it is going to be rough for a while. Bob Farrell says that a bear market goes from caution to concern to capitulation.
Bear markets tend to bring bad news in one form or another, regardless of their shape.
Triangles, for instance, are seemingly moderate sideways patterns. Yet there is almost always a scary event or point of focus in wave e, the last wave, that keeps you out of the next advance. In a large bear market, wave e of an upward triangle correction usually features a bullish event that gets you to buy just before the rug is pulled. Bull markets do it again, only the other way around. They save the best news for last.