I've given up on putting effort in the backgrounds for my comic x) People tend to skim over the panels as they read, so really just a few suggestive lines (doesn't have to be clean) will be enough detail for the reader to make out what is behind the character. At least, I think it beats not having a background at all.
Of course, I'll put the appropriate amount of effort into a panel where the background is the main subject x) but generally, starting this year I'd been putting about half the effort into a bg compared to my characters 