I've noted twice before how Dorothy Gambrell has been very generous by providing her webcomic income information online to everyone. And while she hasn't updated her income graph yet t include December 2010, she did post this as an explanation of why she'll be cutting her updates down to twice a week...
As you can see, her 2010 income was just above $20,000 (as I predicted back in September) but, more interestingly, she's also providing her yearly Cat & Girl income for the past several years, pointing out that her median floats around $25,000. One adept commenter quickly pointed out, too, that her first real decline in income coincided with the overal economy getting flushed down the toilet in 2007 and likely does more to explain the decline there than anything.
But, from a business perspective, it appears clear to Gambrell that the frequency of her update schedule (twice a week versus three times a week) has little impact on her income. Which means that, for the past several years, she's been working harder without any appreciable increase in income. She can therefore spend the time she has been working on a third comic every week to work on other things that are more likely to help her bottom line. Maybe freelance work, or more hours at a part-time job, or more time promoting her comic instead of creating it, or whatever. The upshot here is that whether she updates two or three times a week has no bearing on her income, and her opportunity costs on anything else are going to be equal to or greater than working on Cat & Girl.
So the real lesson for other webcomic creators out there is to pay close attention to your finances relative to your efforts. You may well be doing a lot of extra work without making any more money. That's not to necessarily say that all webcomics should drop to a twice a week schedule, just that maybe you can continue on a lighter update schedule than you are now while still making the same amount of money.
A sincere thanks to Gambrell for her openness and honesty about her finances with regard to webcomiking.