From John Hitchcock's "Dear John: The Alex Toth Doodle Book", this quote is where storytelling begins and ends. It applied 29 years ago when he wrote it and is probably applicable now more than its ever been, except perhaps in the early to mid 90's (cheap shot, I know).
"Economy/simplicity is a welcome, if not vital part of any art form - it is a self-editing process. Comic (books) dwell on "busy" styles today - fans dote on it (more art for the money?) - so, as usual, I'm a majority of one! But I'll go on, my own way, until the last line is drawn - because it serves storytelling best! My aim is not to confuse/confound but to reveal and entertain, perhaps, at times to inform."
-Toth, 28 July, '81
I always end up going back and reading this (pasted above my art table) when I'm thinking "Do I need this _____ in this panel?"