It is hard to say what will happen with different hen to rooster ratios. There are just too many variables and the personalities of the individual roosters are important in the outcome.
One of the problems is that the roosters may fight a lot and injure or kill each other if there are too many roosters for the hens. If they ae raised together, they often work this out with no serious problems but not always. They can change as or after they go through puberty. If they are not raised together, you will probably see a lot of fireworks and it can get real serious. Still, they can often work it out but the process is dangerous and rough. If they are raised together, your odds of them working it out are fairly good. If they do work it out, they make a very good team on protecting the hens.
Another problem is that the roosters can damage the hens by overmating. The dominant rooster will pick out his favorites and the others kind of get the leftovers on down the dominance line. If there are not enough hens to go around, the roosters can damage the hens. A hen can lose feathers due to mating anyway, no matter the hen rooster ratio. With too many matings, she can lose feathers and then the roosters spurs can injure her back or sides. It can be a fatal problem. Since a dominant rooster will pick out his favorites, this can happen even with one rooster and plenty of hens if his technique is especially rough and he really likes his favorite but the problem is much more likely with multiple roosters or lower ratios.
You will often see a recommended ratio for full sized fowl of 10 or 12 hens per rooster. This comes from one rooster being able to fertilize all the hens with this ratio. If there are more hens than this, all the eggs may not be fertile. The more hens the better, of course, but this ratio is not a guarantee that you will not have overmating problems. It depends on the roosters technique and how much he really likes his favorites.
A low ratio does not guarantee a problem either. Many people keep breeding pairs of one hen to one rooster or two hens to one rooster and do not experience overmating problems.
In your case, I would expect you will need remove some of the rooster. Even with 6 roosters and 24 hens, I think the odds of your having problems are pretty high, but it could work out. It's certainly something you will have to watch.
