Usually when the MACD is forming a triangle, it is during corrections where the price bounces back and forth. During strong up trends, the MACD is moving up along with the price and doesn't need nor will form a wedge.
Although a triangle could indicate explosive actions, not all big price moves have to come after a triangle.
Awesome! That makes perfect sense. Your point is also further supported by the fact that so many alts have had that contracting MACD (and they've also been in correction mode for a while). Doesn't have to have a contracting MACD to have a bull run...it's just a good sign that something is about to change.