The question is how many do I need? That is a personal choice. You need Iodine in your diet, you can eat more Seafood, Dairy, Fruits, Vegetables and Baked Goods made with Unbleached Flour (King Aurthur). Basically a Balance Diet from all food groups. 1 cup of Yogurt contains more Iodine (50% of your daily value) than the typical 1/4tsp Iodized Salt (37% DV) you sprinkle on your dinner, or buy Iodized Salt that can't be used for Pickling and some Brines, that's 0 or 1... You like the super fine Popcorn Salt, so there is 2. For Pickling and Brines, a Pure salt is needed. If your recipes go by Volume, depending on recipe, you need both as 1C of fine Pickling Salt can weigh 1.5 to 2X more than 1C of Kosher salt. If the salt is measured by Weight you only need one of these two because 1oz of salt is 1oz no matter what size it is. So that is 3 or 4 salts. Fancy hand harvested Sea Salt, Himalayan and Hawaiian. All have slightly different flavors and textures but with the exception of Hawaiian, if you cook or make brines, marinades, etc, with them you will probably not taste any difference unless you can taste in Parts Per Million. They only stand out, if at all, when used as a Finishing Salt or one that is sprinkled on foods, especially raw foods like salad, at the end of preparation to add some flavor but mostly texture, a little crunch in each bite. So you can pick one of these if you like " crunch " with every bite of food. If just for seasoning, skip it! So now we have either no addition or number 4 (depending on above) or 5, for crunch. Now Hawaiian Salt has a distinctive flavor and red color from the Alaea, clay in it. If you are making Poke, Kalua Pig or some other Hawaiian dishes that specifically call for this type, that is number 5 or 6. Geez I'm losing count! So that is it. Do some research on Salts and the Iodine content of food you probably already eat...
http://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/ and make a decision.
Me, I eat a balanced diet, bake with King Arthur Blue and Red label, use Morton Kosher Salt (7.5oz/Cup) for cooking, brines, etc and Fine La Baleine (Blue Label) Sea Salt at the table...Good Luck...JJ