With JLCPCB it
usually isn't cost effective to panelize multiples of the same PCB, especially considering you'll have to break them apart and you're left with rough edges (if you've ever gotten FR-4 splinters you know).
I panelize 3PDT breakout boards and small things like that because it makes it easier to count and ship multiples. Getting a box of 10000 individual 3PDT breakout boards can be ... fun.
If you do panelize multiples of the same layout you can
usually avoid the charge by ordering 20 or more panels, although at some threshold there is a surcharge for "excessive number of slots" if you have any non-round holes. Regardless of how many are in the panel it is still considered a single design as long as they are all
exactly the same.
For something that ships as a set like the Kliche Mini above, I panelize for convenience, because otherwise I
will forget your breakout board.

These do cost a little extra but it makes it much easier to ship (and keep up with) something that requires multiple parts.
I hand draw those panels. There are programs that can automate the process but I was never happy with the results and I wanted the surrounding frame to make them easier to ship. It's a bit of an involved process but I think the end result is worth it.