Stagnant highs, rising lows most certainly breakout sooner or later. Prices tend to touch both vertices of the triangle till reaching the triangle top. Patience is key in triangle patterns.
@Arunavakp, I personally do not set pre-defined targets for my trades. However, my stop-losses are ALWAYS pre-defined. I check my positions at their price action regions, if they look strong to me, I hold. Otherwise, I sell partially. Generally strength/weakness of a trend can be identified by observing price behaviour at price action regions.