This is just 100% wrong, my friend.

You never know what will be running the day you go out, so you always have a backup plan. Not to mention the highlighted text is the only right part of your post - you can catch multiple types of fish with one rig. So, bring two or three rigs, all of a sudden you have the chance to catch 6-7 different types of fish. This is pretty typical, at least in South Florida. A fisherman might go out for Mahi, and then sees some Tuna running. No fisherman worth his salt is going to just let the Tuna do their thing and keep looking for the Mahi, especially if they're not hitting. He'll switch rigs (or more than likely he'll have a couple pre-pared) and bam, he'll be Tuna fishing.
Man, I don't know why I'm even bothering, because it is so beyond painfully obvious you don't fish. But, I will anyway because I'm a stubborn ass
You do know what's running before you go. You know why you know? Because only certain things are running certain times of year, in certain weather conditions. there are also constant fishing reports. You know exactly what you can catch, narrowed down to no more than 2 or 3 species, before you ever step foot out of your door.
Not all rigs can catch multiple species of fish. I don't know what would lead you to assume that. A simple leader will catch your basic small fish that a one armed leper that doesn't know what a fish is can catch. Things like black bass, croaker, oyster crackers, hogfish and spot. These are fish that people who fish more than once a year don't intentionally fish for at all unless it's for bait. They're small, you need a thousand to make a meal (in the case of spot and croaker - the only two of these normal people eat) and they put up no fight. It's a boring catch and takes nothing more than a piece of bait in the water to catch one.
On a real flounder rig, you have 2 choices. You can set up a jig, with a weighted end and a trailing piece of bait (which bobs along the bottom where only a flounder will get it) or you can use a snafu rig with a circle hook. Other fish will tear your bait off once in a while, but 99.999999% of the time, only a flounder can get it in their mouth. So it's a one species rig.
Stripers/Rockfish are something I won't go into, because you are almost certainly only fishing for that with a larger rig too big for other fish when you're after them. One species rig.
When you're going after reef fish like grouper, roughy, snapper, etc. or sheepshead and spadefish, you can use the same setup with each - a simple bobber with a crab or clam on the end, right up against a structure. These essentially end up being a one species rig, because even though you can catch any reef fish with it, you aren't going to have multiple different types of reef fish all together in one spot fighting for your affection.
Pompano is another one with a specialized rig. As are Tuna, Mahi-Mahi, and the vast majority of fish. Mackerels have their own rigs as well. So if you bring 2-3 types of rigs, you realistically have the possibility of catching 2-3 types of fish under almost all circumstances, not 6-7 unless you're catching the bull**** fish I mentioned earlier.
For 30 years, I have fished all up and down the east coast, the gulf and the bay. I have fished from shore, boats, piers, deep sea trollers and bridges. I have fished for every type of fish you can fish for in these areas, and have had loads of success doing it. In the winter, I fish at least once a week, in the spring and fall 3 times a week, and almost every day in the Summer. I have gone in all types of weather, all times of day, and never for less than 4 hours at a time. In the Summer, it's usually 6-8 hours each time. In other words, I'm not talking out of my ass, I have more knowledge of fishing than just about anybody you will ever meet.
You keep saying everything I'm saying is 100% incorrect when it isn't, so I'm just gonna bang my head on my keyboard and salute your stubborn ass for out hard heading me..........this time
Fishing is something I have immense knowledge of, and quite honestly I don't think you fish at all and you're just trying to frustrate me. Maybe I'm wrong like you
I just don't want this to turn into a pointless shouting match. We can agree to shake hands and walk away for a change I think. But I'm warning you now, I'm hocking a loogie in my hand first.