I wouldn’t bother trying to resurface enameled cast iron, but regular cast iron is easy. Sand off all of the flaked/blistered stuff, right down to bare metal, getting it as smooth as you want (smoother is better, IMO). A palm sander works fine. Inspect it VERY CAREFULLY for cracks. If you see any cracking, even the tiniest, toss it. Then reseason it by your favorite method. The Lodge website has plenty of information on this.
I’ve had my cast iron skillet for almost 50 years, though I no longer use it every day. My mother had a 70-year skillet, but I don’t know where it went after she died.
Our many cast iron skillets are in great shape, but at various times they have all been more or less abused, but I never follow the formal seasoning process.
If one gets over-heated or left wet and rusts a bit, I just scrub and scrape as necessary to get it smooth, then put some oil on it and start using it correctly again until it slowly builds up to a nice dark surface again.
I find the edge of a metal spatula makes a great scraper tool, and a regular scruber pad. I don’t worry about it if I go down to bare metal in a few spots.. they always get “seasoned” by using them.
Obviously, you don’t want to over-heat them or let them rust, but accidents happen - and I’ve never bothered to do the whole bake-in-the-oven thing.
If she was smart, she took it with her! Heavenly pancakes, eggs, bacon, etc. to die for...
I have my grandma’s, then my mom used it, now I use it, The big one you fry a whole chicken in.