I love to feed the herd. To see them multiply is just too rewarding. But there can be too much of that good thing. If you just add food, your worm bin will eventually burn out and the worms will not be happy.
There are two living beings in play. Obviously, the worms are our focus. They have busy, happy little lives going on in the bin. But the bin is alive too. Just a peek shows that there are a lot of other crawly things sharing the worm house. Even more so, there are a bazillion invisible critters swimming around and driving the compost breakdown. Those invisible bacteria and fungi are prey for the hungry worms.
So, if you want happy, well fed worms, you must feed the bin that feeds them. Microbes eat the food dumped in and the bedding too. The microbes need bedding and food mixed just like an outside compost pile needs a blend of greens and browns. Food is the nitrogen rich greens and bedding is the carbon filled browns. Add both for healthy growth.
We aim for an initial 30 times brown bedding to over-balance the green / brown ratio. That mix buffers the food and provides structure. As the bin matures, judge how heavy the bed has become. It needs to maintain a fluffy, spongy quality that you learn to recognize. Occasionally stir in a handful of shredded cardboard, paper or leaves to see if the bed looks better in a few days or do you need to add more.
Completely broken done bedding is thick and dense. That rich vermicompost is the good endpoint. But before the ending you need to keep the bed freshened. Fresh bedding lightens the bed for easier digging and crawling. Your microbes consume the fresh bedding with the food scraps to make a healthy dish for worms to slither up and dine. Have a nice dinner my fine herd. Enjoy the browns you helpful microbes.