Cast iron cookware is comparatively thicker and retains heat much longer than any other material. This helps create a beautiful sear on everything you fry. Not just fried food, even curries benefit from being cooked in cast iron Kadai.
No matter how long you use a cast iron cookware, it never becomes non-stick. Rather, it improves the stick resistance. Even then, you have to use a sufficient quantity of oil. Else, the food will get stuck on it.
Cast iron does not conduct heat evenly. The centre is always hotter than the edges by around 40-60° C. This is why you need to preheat cast iron for at least 5-10 minutes at a low flame before you start cooking. This helps reduce the temperature difference between the centre and the edges.
A few people say that cooking acidic food damages the seasoning and food will get stuck on it, and hence, it should be avoided. However, as per research, moist acidic food absorbs more iron from cast iron cookware, compared to others. Hence, to maximize the benefit of cooking in cast iron, occasionally cook tomato and tamarind-based food in it.
To protect cast iron cookware, simply clean it after use and apply a thin layer of oil before keeping it away. If you do this for a few years, the cookware will develop a thick layer of seasoning and eventually, it won't rust even if you don't oil it.
Cast iron should be stored in a clean, dry area preferably away from the cabinet under the sink. Always, keep it on top of a thick cardboard sheet so that rust from cast iron doesn't discolour your cabinet shelf.