Sharing or not textures according to different atlases?

Question

3D

Hello!
I can not decide, I need help)
I am working on a game in which you can collect ships from 4 parts (each). Got a question. Create a separate atlas for each part, or how to group them into sets (although in the end it will be possible to set them randomly not in sets).
The question is that if you make separate atlases, there will be PPC how many of them. And for example, if the part is small (compact engine), then the atlas will be redundant.
On the other hand, the more atlases, the more memory they will take (although I do not aim at mobile phones, but nevertheless I want to capture low-end computers).
And in addition, I know that for betting, it is desirable that the details are finally on the same atlas.
How to be?