For some things where you want to learn but don't want to/have time to put in full effort premade cards are better than nothing. For example, I ended up learning German to B1 level from Duolingo (+ friends/time in germany) because using Duolingo was pretty low effort, even if it wasn't the fastest most effective way of learning.
I think this is probably true for most things you may want to learn about outside of your job, school, or really strong reasoning behind it. Perfect is the enemy of good as they say
(Shameless plug: I made a tool that makes spaced repetition questions for educational YouTube videos/podcasts that you watch, usually I was forgetting everything and wasn't really that invested to spend the time making decks for everything I watch, so I landed on this! https://www.platoedu.org)
I really wish Claude had something similar.