How do you typically prototype card games? Looking for insights

Hey r/cardgamedesign!

A couple of days ago I shared a prototype I’m working on over on r/boardgames (e-ink playing cards, you can have a look here), and to my surprise a lot of people said the idea might actually be more useful for prototyping card games than for playing finished ones.

That caught me off guard because I realized I actually know very little about how designers prototype their games in practice.. tools, workflows, pitfalls, what helps, etc.

So I’d love to hear from people who prototype regularly:
How does your process usually work, and in what situations would a tool like this be useful or not useful?

I'm just trying to understand the design side better and learn something new from those with experience :)
Thanks for any insights! 🙏