I've been making ginger beer once a week and dividing my culture each time. Today I weighed how much culture I have and it is less than 100g. I've been advised to try to maintain it at about 150g. So I haven't divided it this week, but I'll try to build it up.
It's a bit like having a pet. You can't neglect it, you have to be faithful in feeding it, and making sure it is at a reasonable temperature, and keep an eye out for its welfare.
I have three cultures at the moment that I'm maintaining - Fred, the ginger beer plant (pictured), Fizz the sourdough bread starter, and my yogurt culture who doesn't have a name.