If this is true and you aren't too much of an outlier, it would go a decent way to explain the failure of a good chunk of educational theory in the past few centuries.

The basic idea works for me, but I think Tom's simplifying it. It's not about "add to Anki with 0% understanding" vs "gain 100% understanding when first learning"; instead, it's more like "add to Anki with 80% understanding" vs "gain 90% understanding, having had to spend several hours for the extra 10%."

Far too many people tend to get hung up over that one thing in a chapter that they can't understand. More often than not, it's something they could understand perfectly if they just said "meh" and read a few pages ahead, but no; they just stay stuck on that one spot, thinking "wtf is this??!!"

Also, far too many people read books word-by-word when they could get essentially the same amount of information by skimming over the pages. Anki helps here, as it forces you to extract the relevant pieces of information from the text, (or at least stuff that looks important) instead of letting you comfortably wade through a wall of text and believe you've understood it.

(It seems, on first glance, that these two paragraphs contradict each other, but they actually don't. The third one is talking about stuff that looks easy but actually isn't, the second one's talking about stuff that looks difficult, but wouldn't if you'd just read ahead.)

Also, you generally don't have to wait until later for insight into whatever you've failed to understand... More often than not, insight strikes even as you're adding the cards.