Knowing something just is not going to work out is good. It gives u an opportunity to change your course and do different things. Getting to this point is rather easy as long as u bring the right attitude. An attitude that lets u test and play with code.
A start up life at its best is like a loop. Do something , see if it works, try something else. But sometimes it is not and most of those times u end up wasting a ton of time, money and energy. Damn. Like a loop sometimes u do not even know what got u into the mess u just know u want to stay the hell out.