Meh, so what? Your hobbies don’t need to be regulated or on a schedule. They should be fluid, not rigid. I don’t subscribe to the theory that near-obsessive traits are required to claim an activity as a hobby like msmith537 does. For me, a hobby is something that I enjoy doing. I don’t think it requires any staunch commitment whatsoever. Some years I’ll homebrew 40 gallons of beer, other years 10. Other guys brew hundreds of gallons a year. It’s still a hobby of mine. The fact that other people do more of it than I do or are better at it than I am doesn’t mean I’m a poser. I brew my own beer when I feel like it, because I enjoy it and I want to.
I’m a certified scuba diver for the past four years. I didn’t mention it in my original response because I’m not diving twice a month or more. It’s not possible where I live unless I wanted to dive in freshwater lakes (I don’t). I take one dedicated dive trip a year and make 8-10 dives over 4-5 days. Last year I got in a single dive day on a road trip to the Florida Keys, because I was there and there was diving available. It’s still a hobby.
If I enjoy doing something and I haven’t actively, consciously stopped doing that activity, I consider it a hobby. There probably is a time limit on it. The time limit is flexible depending on the activity, but I think a year is a pretty good benchmark for most.
When the time comes that I haven’t been on a dive trip for two years, I probably can’t call diving a hobby unless I have pretty solid plans for a dive trip. When the time comes that I haven’t brewed a batch of beer for a year, I probably can’t call home brewing a hobby unless I have ingredients in transit. When the time comes that I haven’t fired up the smoker for six months, I probably can’t call BBQ a hobby, etc. Whenever I’m willing and able to pick up the activity again, it’s one of my hobbies again.
I don’t want to feel obligated to my hobbies. If I’m not doing it for my own gratification on my own schedule, it ceases to be a hobby. This doesn’t mean you can’t be obsessed with something and still enjoy doing it. It means that you can enjoy doing something without being obsessed by it.
If your hobbies aren’t fun anymore and begin to feel more like obligation than leisure, you need new hobbies.