In my experience (I have over 10k flashcards in Anki and SuperMemo) it takes a lot of time to create the cards (vs. repeating/learning them). But the main reason is because I have to take time to think about and understand the content first, reformulate it in my own words (otherwise it won't stick well!), and cut it into bite-sized cards. What helped me most were articles "teaching" how to do this, or generally the experiences of others [1] [2].

From scanning your product's landing page, it seems you focus a lot on the time-savings during card creation, by relying on copy-and-paste. I'm not sure this is the best way to learn more complex topics, but may work fine for very clear things that are already bite-sized in the source material (e.g. chemical formulas, or language vocabulary). Are you focusing on these use cases?

[1] https://andymatuschak.org/prompts/ [2] https://news.ycombinator.com/item?id=24878171