If the mind is not in the right space it is harder to find or create a shot as well. I find that if I force myself to find something to shoot, I end up with shots that look like I was forced to shoot them. I have no problem with walking away from a place with no images if the light is poor, the place does nothing for me or my mind is just not into it. I am a amatuer and as such I have that luxury and do not want to waste my time processing and printing images I do not like. That is not to say one cannot work a place and find many very interesting images that were totally missed on first sight but there may not be anything there for you that day or some days there is nothing for you anywhere.