Let's say the setting is Atlantic ocean, and I'm trying to nuke New York. I have one sub and yet I could use all 5 nukes or possibly 3 to hit the same place at the same time by setting when to launch. There would be an edit to how you want to launch your nukes before actually launching or rising from the water so the program is already running.
Then, all your launches, lets say 3 will hit New York at the same time. Same with silos. You can synchronize the launches with silo and hit your target effectively. But the problem with a MRBM launch is that a nuke has a certain fuel capacity, so if you need to hit a target pretty far then you can't synchronize.
So this is how it would work... You launch your nuke higher that the other launches, then the second nuke doesn't go as high as the first one. Then finally the third nuke would go the least highest and all nukes would hit the targets at the same time. This only would be effective from a reasonable distance from the place or object your aiming for. Cause if its too close then you won't have a chance of launching all war heads. If it's too far then the highest nuke wouldn't reach it's target. I hope this makes any sense to everyone cause it is kinda complicated
But this would increase the possibility of hitting something without many forces and units. 
