Last flax for us was 15 years ago.   As the old timers used to say, if you plant flax long enough you'll eventually run out of seed.    Flax does good the first few times it's planted on virgin ground, then things get ugly.   Plus, ANY crust at all, and it won't come up.    We usually planted at 52-55 lbs/a.    If conditions are good, you didn't need that much, but if it crusts, you need all the help you can get.