I grew up camping and remember being shocked at charcoal on a DO. I must have been young.
The thing is that charcoal is consistent. You can count it and the same count makes the same heat, mostly. That let's you be precise easily and helps you learn. Without it you'll burn more and have more late meals.
If you want to use formulas just estimate how many bricks would make the coals you use. Sure wood varies more. Some woods burn hotter and most burn faster, just pay more attention. I learned to heat the ground with the fire first and not put coals underneath. But I don't always do it that way. And practice on family, not guests!