I do in fact use twigs all they time. They are easy to get going for a fire and produce heat quickly. But they do need a bit of refinement as to their handling. Here's what I do.....
In the course of ground maintenance I come upon windfallen twigs all the time. The best thing about using them is that they are dead and quite dry, ready for burning. And they are usually brittle enough to mostly break up by hand. So when I'm doing cleaning up or pulling weeds, I'll cast the twigs into a pile as I move along. Then later I'll come back for those small piles, gathering them up in the wheelbarrow to transport them to a central location for processing, usually the lowered tailgate of my pickup truck. It puts the twigs at a comfortable waist high.
By processing I mean turning them into twig faggots. I had seen a picture decades ago of an Italian farmer who made twig faggots by lining up equal sized twigs then tying them into a bundle with string. I tried that and it was far too tedious and wasteful for me. It took my forever to make a pile of faggots that I burned up in just one evening. Plus they were still awkward to get into a burning stove. So I abandoned the idea. But since starting this homestead I revisited the idea. I had scads of twigs here that had to be of some use other than being just landfill. So I experimented.
The method I came up with that works for me is to make rolled up newspaper twig faggots. The beauty of this that even tiny twig pieces get utilized and no need to be exact while breaking up the twigs. I'll use one sheet of folded newspaper to make a faggot. I could use more but one seems to do the job. I'll lay out the sheet as shown......
Now I'll break up the twigs and pile them on so that they don't go much beyond the edges of the paper. Why? Because that's the length that fits into my stove.
I don't try to make the faggot too thick. Thinner is better than thicker. If there are too many twigs it is difficult to roll the faggot and make it stay rolled. And if it's too fat, it's harder to put into the stove.
I'll roll a faggot then store it in a suitable sized cardboard box. As the faggots fill the box they hold one another together. The cardboard box is also lightweight for carrying, keeps any dirt or twig bits from messing up the place, and is a handy way of storing them.
Making faggots this way means that any size twig can be used. There is no need to be neat and careful. There is no string tying. Rolling goes fairly quickly. Anything too thick to hand break or crack over the edge of the tailgate or under my foot gets put in a pile for cutting up with the chop saw. So there's no waste either.