That was exactly my experience. I tried this method many times, thinking I must have made a mistake each time, but it was always the same result. The seasoning would work beautifully for a short while, and then it would flake.

Luckily, later on I learned a better way - a cooking spray called Baker’s Joy, which is essentially oil impregnated with a little flour. The flour seems to help speed up the seasoning process, so you can get to a well seasoned pan quickly. I usually heat the pan up, either in the oven or on the grill, then spray the Baker’s Joy when it’s still very hot. I make sure the pan is well coated, then I wipe out the excess.

This technique won’t give you a hard shell like the flaxseed oil method does, but it does seem to produce the same results as multiple seasoning sessions in a single pass. I’ve also found that cooking an onion in the pan helps when the seasoning isn’t quite what you want it to be yet. I read once that it’s a traditional method for breaking in a carbon steel wok.