For user pans, I've found that frying potatoes does a good job of finishing the seasoning process. For the first batch, I add grease, oil, or Crisco (whatever I have on hand), slice a potato and fry it until over done. A little smoke and burnt potato bits are good! Toss the potato and the grease. This removes any lingering metallic taste and odor. Add another batch, this time for eating and fry them up.
After frying those taters, don't wash the pan. Pour out the excess fat. Use a paper towel to wipe out the rest. Then, use that same towel to wipe the outside of the pan. Doing this a few times yields a hard finish that'll handle gravy. It'll take a quick washing in hot soapy water, too. Just dry it, heat, and oil, if the seasoning shows any sign of breakdown. After a while, there won't be any. ;)
For cornstick pans I do something similar. After seasoning, the first batch of cornbread is thrown away. I overcook that batch, too. Sometimes it takes a fork to break loose the bread that's stuck. Soak it in plain water for the minimum amount of time it takes to free the bread residue. (Put water in the pan, don't put the pan in water.) Heat the pan and oil it again. Make another batch of bread. (I bake mine at 450*, BTW.) After a few times, the seasoning is set.
In each case, the more the pan is used, the better it gets. I try to use a "new" pan as much as possible over the course of a few weeks until it looks like it's been used for 10 years. And, then for seldom used pans, they get pulled out for a potato fry now and then to keep them well seasoned. FWIW, I've found that method to be the easiest and most economical way to keep them looking good.
Hope some of this is useful.
Lee