I think one issue in this thread, at least for me, I'm not sure if we are talking about a locked triangle, or legs crossed with arm in--or "ready" to triangle. In the second scenario, that's where I'm keeping one eye on my fallback options if it doesn't seem like I can get his posture under control and advance the triangle. Against a tough guy with good defense, in my experience, if you don't slap on a locked-in triangle from the start, you aren't guaranteed at all to finish it from the "ready" position...odds still in your favor, but not overwhelmingly so--heck, my instructor will do this fuck-your-triangle, posture and gi choke from the "ready" position all the time...so it is even possible to be submitted.