The way I see it....if its not possible to release an update every 1 to 3 months, 6 months max, these devs should NOT be charging monthly and should be charging PER release instead. A few devs (more than a few actually) in these forums pushing a single update per year with very little content. I get that they might have full time jobs but that just brings me back to my point....charge per release. People will still complain either way.
You have devs that deserve the support releasing updates monthly or every 2/3 months with quality content and aren't making much and you have devs releasing 1 update per year with 5 10 minutes worth of content and raking in serious cash. Twisted world we live in lol