Seems there's no specific limit to the amount of ships that can turn up in a system. Seen a lot of very busy systems where certain ships came up to the station, and other - completely different ones - only ran around on the planets. Basically, find the trade stations and hang out there for a while. But yes, sometimes the variation is almost completely absent.
I.. suspect there are three reasons for that. One is that likely the basic premise for deciding a range on the designs is based on the location in the galaxy (they're supposed to be unique to the location you are in - which they are). So if you jump through a black hole, end up on the opposite side of the galaxy, you get a lot of weird designs compared to what you had before. But if you travel a path for a very long time, you sort of recognize parts of the transformation range on specific parts (I'm weird, I notice things like that, sorry).
The second one is that some of the designs unlock over time, or likely with exploration level. Some of the variation is more extreme on the white and blue systems, but the basic extra wings and so on simply don't turn up before you level. It's difficult to confirm this, but it seems consistent with the entire Atlas path. Some of the extra spikes and bent wings simply don't turn up early on.
Third is probably that the planet location spread has something to do with the ship spread as well. I.e., the ships spawned on certain locations have these unique final variables just like the planets. And I think that when the planets were bunched together, this affected some of the creature and ship spread as well, and was never "tweaked" in the same way.
In the same way that when you have so many stars in each cluster on top of each other, it's very easy to travel to a system nearby, with the same lack of spread, and therefore get these basic designs that look pretty much exactly the same. This put together then likely conspires against you so to speak, since you tend to not jump three-four times in a row before you start exploring again. So not only do you not get different base models, you also get similar variation.
On the other hand, the few systems I find with planets spread out far apart (relatively speaking), these also consistently have the weirdest designs. Assymetric wings, variations on the same scout over the base model that are different even in the same system, etc. And of course - not all planets spawn ships, and you can just be incredibly unlucky with where they spawn (i.e., at about the same spot).
Kept grinding transmission towers for a long time, for example, and actually got the same ship (in different locations). Like some spot, you have certain systems that just flat out spawn a squad with the same ship - this is likely connected to that. That in this particular location in the galaxy, the spread between the variation seed simply didn't exist.
Would.. love to have a talk with whoever signed off on the idea to bunch everything together, to be honest.. To hear their point of view on what they thought they were doing (because I like hearing crazy people explain things that make sense to them... *cough*).
