I don't know that there is such an animal. If there is, I've never seen it. But, don't despair. You can do this. Boyer's and Ratigan's books will help, but the best way to learn, in fact probably the only way is to sit down behind a rifle and flags and practice. It seems to me that many folks want to know exactly where to hold when flags are doing some such this or that other thing. This is never going to happen. Every range is different and every day is different, even times of day are different.
What you need to study is where the bullet impacts in relation to what your flags are doing at a particular time and place. I believe the only way to do this is to shoot every practice session with flags and don't just pick the calm consistent days, but rather make an effort to practice on seriously bad days. There are tips and hints available in the above mentioned books, but practice with flags trumps everything and I don't believe there are any short cuts. My personal experience is, flags will not tell you when to shoot, but they will surely tell you when you shouldn't. If I am wrong I will happily accept correction and will apply the advice given.
Rick