Flaxseed oil. Meh. It is expensive, it calls for 7+ coats if I remember correctly. It smells worse than any other oil I've ever used to season while seasoning and that's pretty bad because Crisco is gross smelling. Lol. Hanging around the cast iron community, I have talked to a lot of folks that know a lot more about it than me. The general consensus of those "in the know" is a resounding "pass" on the flaxseed oil. It just doesn't do anything better than any of the other oils. And it is ridiculously expensive.
My personal experience is that I have had 2 pans flake badly after a couple months use and had to be restripped and seasoned. I have one more that is used pretty regularly that just recently has showed some signs of needing some attention. So, yes, it worked. Kind of. But at the cost, I will take my $4 tub of crisco all day every day over flaxseed oil. Just my 2 pennies. If it works for you, great. If you're on the fence, spend the extra 10-12 bucks you save by buying crisco on amother skillet or two.
I've done most of my cast iron with Crisco or vegetable oil. We have three skillets that get used the most. The big one is used almost daily, browning, searing, sauteing, you name it. It gets cleaned the most and needs to be re-coated with vegetable oil the most.
Our smallest skillet is used almost exclusively for frying eggs, over easy in butter. That skillet is never washed, just wiped clean, and it's developed the nicest slick black surface of any of our cast iron.