For a given draw weight, on a given arrow length, a particular FOC will work best, but if you design your arrow, keeping in mind that your trying to get it as high as you can for that combination, then any FOC can be made to work. If you lock yourself into a particular arrow, draw weight, or arrow length, then you will not be able to tune an arrow for best flight at anything but one particular FOC.

This is how I tune for a very high FOC:

First, pick a heavy broadhead, and a weighted insert. Personally, I try to get this to add up to at least 225 grains.

Then, pick an arrow spine that I know is a bit too stiff for the weight I have up front and the expected arrow length I'm likely to shoot.

Assemble test arrow at full length with insert put in with hotmelt glue. No fletching yet. This should leave you with an unfletched shaft that is too weak for your setup.

Bareshaft tune for perfect spine by cutting the arrow length 1/4" at a time, until it is stiff enough.

Assemble the rest of the dozen, using good arrow building techniques (cutting from both ends, spine testing, broadhead alignment, etc). I use carbon shafts and helical fletching, which gives me the lightest backend I can have, which in turn, increases FOC further than choosing heavier components.

Once assembled, you can further tweak dynamic spine if needed by adjusting draw weight slightly.

Using this method, I have gotten a huge range of FOC arrows to fly exacting like they should. You can even do this with an 8% FOC and it will give it the best flight it can have. It's just that higher is more stable, so that is what I aim for. If I wanted an even higher FOC, I'd chose a stiffer shaft and put even more weight up front. Using this arrow designing technique, the higher the FOC, the greater the total arrow weight. When you get into that 20-25% range, it gives you an arrow with almost unbeliveable stability and penetration. Until you shoot an animal with an extreme FOC arrow, it's difficult to comprehend just how good this combination is.