Okay here’s the thing you literally have a container launcher each pod has a missile in it. In fact every rapid firing missile system uses multiple pods and launches 1 missile per pod. The container launcher from the Companion is the same. Great for a single punch but how l9ng did it take to reload those pods once fired?
A missile rack has a single rocket pod that’s has a reloading system, a Barbette has 5 rocket pods with a reloading system and the bays have 12, 24 and 120 respectively. That’s literally how it’s described in the CRB and HG
We reloaded in 3-5 minutes if we were in a hurry and nothing went wrong on us. Reloads were pre-positioned on the ground by the ammo crew (I did both). Two pods are dropped about 12-18 inches apart. The launcher pulls up alongside the pods, the LLM (the launcher) rotates - usually - to the opposite side of where the reload pods are, you drop the empty pods, spin the LLM to the new pods and pick them up. Each bay has it's own cable/pulley system and you have some leeway to pick them up (i.e. it doesn't have to match perfectly), hook on to the pods and reel them up and stow them. Stow the LLM in drive mode and off you go. It was pretty straightforward and fast. Because the rate of fire was so high each launcher has two ammo trucks w/trailers so that you have 16 total pods per launcher for ammo. We never had ATACMS, but the whole pod is same size, if a bit heavier, same principle applies though.
VLS systems on Navy ships are essentially the same way - each missile is in a self-contained pod, and you can ripple-fire them almost as fast as each missile clears the launch tube. I don't know the launch velocity off top of my head for a Standard missile, but MLRS missiles are going supersonic about the time the rocket engine clears the tube. While it's rare to fire multiple missiles at the same exact target, you can. In that case you can ripple fire them every second. If you were doing area denial (like an entire grid squre, which is 1km by 1km) the launcher has to reposition itself between rounds, which is why the ROF is 5 seconds between rounds.
One thing about naval VLS systems is that the Navy is just now deploying a reload capability to reload a ship at sea (under really good weather conditions). Otherwise they have to return to port for reloads. For MLRS we did it in the rain, the mud, all weather - we just were not happy campers to do so. Obviously in space reloading a ship is under vacuum and zero-g conditions, so not as fast as MLRS, but not as long as VLS. Plus in combat you can't do anything other than what is in your magazines, so the reloading is for combat. You'd call up your fleet train to perform the re-ammo process for your ship.
The thing that gets me with the reloads for any Traveller missile system is the time. It's way too long. I think some of that come from the original LBB that literally had a crewman manually reloading missiles (stupid!). The Oliver Hazard Perry Mk13 missile system had a single launch arm and two rings of missiles and it's firing rate was every 8 seconds (this included rotating your rounds, loading them from below deck and the arm moving to firing position (angled) and then going back to a vertical position to take the next load. Machinery should be far faster for reloads for such small missiles. The last of the twin-arm launchers for the Navy was the Mk 26 and it had a ROF of 2 missiles every 9 seconds.
Personally I think the descriptions could use some tweaking. "A turret can launch up to 3 missiles per round, a barbette can launch 5 and bays can launch 12/24/120. Ready ammuntion (w/o additional magazine storage being allocated) is ....". Using terminology like pods is confusing and inaccurate. The ready ammunition may also confuse those who are not savvy on that term, which can easily be tweaked to being "ammunition stored on-mount" or somesuch idea.
Based on the tonnage allocation I would discount the ammunition storage other than 1 round in the pipe(s) and one round in the reload machinery. Anything else requires tonnage to be allocated. Otherwise a single turret costs you one ton, you get 12 rounds (which also are supposed to displace one ton) and your reload equipment, access area, power systems, etc, are all given for free. When the LBB's were first published everything was very basic. However when HG came out (and later iterations started providing more details) this was never looked at and the free space conundrum has continued. Not how I'd have done it.