Someone emailed me the other day about my drawings and somehow they got the impression that I never do dirt ruff sketches. After looking at some of my posts over the last couple of years I can see how you might get that impression. Truth is, I will do a lot of exploration with thumbnails to help me get where I'm going. If I can't get with what I'm after with a certain pencil, I'll switch off to some other pencil, marker or even a plain ol bic ball point pen, which is what you see here. Some of these sketches were done looser than normal for me and took no longer than 30 seconds to make. Because you're not investing a ton of time into the sketch, it's easy to discard and move on to the next. Like most people, there are times that I'll hit a brick wall. In those moments, it's best to walk away for a couple of minutes and clear your head. Get some reference, live action video, photos or look at other drawings that are similar. Go back to the board and use the reference to help you get the result you need. Worst case scenario, get another artists opinion and see if they can help solve the problem. Sometimes the solution is very simple and you were complicating it.
It's not a bad idea to look at the drawings you had previously done before becoming frustrated. Sometimes there's a gem in there and you glossed over it because you were caught up in the heat of the moment. BTW, the drawing on the bottom, is also a thumbnail drawn in a bic pen, but sketched a little slower.