yeah, I know that feeling all the time... I've got a pretty active and picture-filled and based mind, but everytime I try to bring it down it looks... well 'underwhelming' to put it charitivly... (argh, fingers why don't you match the lines on paper with the ones in my head >.<)
Not really, not anymore at least. When it comes to architectural things I can usually do anything I want, as long as I have enough time (a few months perhaps?) and patience. The amount that the finished product falls a little short is sometimes the part of it that makes it fun- I don't believe in reproducing photographs, so I consider the effects that clearly make it a drawing and not a photo are an important feature of a drawing. If I was just creating a photo with nothing different from the reference, then why I am I wasting all this time? Why not just print the photo on a piece of paper and be done with it? I don't believe in "skill level" either. If I really want to draw a certain thing, like a realistic portrait of a real person- well some more practice and I'd probably be able to do it. But I don't want to. It's not what I find enjoyable and not what I want to express. Part of me also believes the children who waste their time on stupid cartoons could also draw a decent portrait- with the right teaching and patience and practice. The choice not to is theirs.
I suppose it depends on how focused I am on the idea in question. If I'm tossing around an idea, or a thought, and it doesn't come out right on paper, then I keep trying again until it somewhat resembles what I'm picturing in my head. If it's something I really want to do well on, and it fails...I normally just give up and move on to another idea or thought. It's probably not the most productive way to do things, but that's been my method ever since I picked up a pencil.
Well, if it works for you, I'm not going to be against it I will have to admit, if the idea isn't clear or something that doesn't readily excite me or motivate me, I'd probably disregard it, because it probably won't be one of my best works.
On the other hand, if it did, and it still didn't turn out right...if I had the time/patience I would redo/restart or come back after I've improved.
This happens all the time, usually I will just give up and try again another day. I think, most of the time, it is because I rush into it too quickly because I am eager to transfer the idea to paper/canvas.