Yes, you're right. For big structures, multi-line formatting is used, for smaller, one-liner is used.

It conforms to the Ruby SUSE Style Guide, Arrays and Hashes:
https://github.com/SUSE/style-guides/blob/master/Ruby.md#arrays
https://github.com/SUSE/style-guides/blob/master/Ruby.md#hashes

Although I forgot about this style guide, my code came to the same (or very similar) state organically.