This is one of those "one that got away" stories that provides a lesson.
I bought Xerium (XRM) as a lottery pick early in May (see upward-pointing arrow). It looked to be on the cusp of a cup with handle breakout. I was disappointed that it didn't break out, and it actually sank away from the breakout point.
After a week, I grew tired of this stock "doing nothing", so I dumped it. There wasn't any technical reason for doing so (because I had bought it in anticipation of a breakout, so there was no "violation"); I simply wanted it off my screen since it wasn't performing. (Down-pointing arrow)
It took a couple of more weeks, but then the stock really took off – — just as I had originally expected. The lesson? Being bored is no reason to get rid of a position. Sometimes things take longer than you expect.