This seems contradictory at first glance, if you didn't actually implement it then how well have you actually understood it? It's known from learning theory that engagement or even self-reported understanding doesn't imply that the student can actually solve problems presented to him.

If someone claims to have "understood [middle school] algebra" but they aren't able to solve equations by themselves, you'd be skeptical. Of course past some point of familiarity it's simply faster to throw things into a CAS, but if you remove the initial manual struggle, then have you wired up your brain for understanding? There was a post on HN a few days back about how familiarity with a tool leads to a sense of "embodied understanding" [1], and I think the initial struggle is an intrinsic part of learning to get to the "unconscious competence' level.

[1] https://news.ycombinator.com/item?id=47640775