Figs are a problem as most companies have not tested figs. Hopefully with their rising popularity, they will spend the money to test. i would follow label directions for fruit trees. Most copper sprays are very weak these days, one needs to use a Kocide copper product (copper hydroxide) for them to be effective. Also using a sticker is just as important, maybe more so than the copper itself.
Copper will stop fig rust before you get it, it though only really works as a preventative, once you have it, it is not going to eliminate, although may protect unaffected leaves.