When it comes to my art, there are very few times where I felt like I actually did the best I was capable of. I mean yeah, most or all artists look at their work and say "Gawd this SUCKS!" but the reason we're like that is because we feel like we should be able to do better. (Or at least, that's why I'm like that. Other artists may vary, I suppose.)
But the thing of it is, usually I am trying my hardest. There have been times when work escaped that I had no business letting loose because it was a half-vast job ... at conventions, mostly, which is why I have taken to doing fewer pieces and charging more, so I can do them right instead. There are a couple of pieces out there that I am flat-out ashamed of, for just that reason.
So if I'm trying my hardest, but still don't feel like I'm doing my best, that means that somewhere between effort and execution all the quality is falling out. ¬.¬ Or to put it more nastily...
"I did my best!"
"That was your best?"
It may sound funny, but I am quite serious when I say that one of my big plans for the hiatus period between SJ - the strip and SJ - the comic is art lessons. I have never had any formal art training, but have gained what skill I have from studying other people's work and reading lots of books. My art has certainly grown by leaps and bounds between this and this ... but it's got a long way to go before it gets comparable to this or this.
I'm hoping that art instruction will improve my technique (and hopefully expand my repertoire) so that there are fewer times when I feel like there's this enormous, unaccountable gap between "trying my hardest" and "doing my best" ... it really sucks to knock yourself out on a piece only to have it come out a bunch of junk. I don't expect to be able to just toss off beautiful stuff right and left on a whim -- although that'd certainly be nice -- but I do want to be able to put down the pencil after a few hours' work and not be ashamed of the result.