Yeah, I basically have no choice but to deeply, truly understand something. If I don't "completely get it", I will struggle endlessly to employ the "knowledge" I have. It's been a lifelong challenge (indeed I barely finished high school because I was actually failing classes because it was impossible to keep up -- yet I am a senior software engineer today), while some people forge ahead seemingly effortlessly, I am still solidifying the fundamentals. To be fair though, my deep understanding of stuff results in pretty comprehensive/effective solutions that consider edge-cases/gotchas/etc. and I think that's pretty valuable. Once I have those "fundamentals", I have mastered that shizzle and it's completely solid in my repertoire basically forever. The decay is VERY slow once I learn something, and I can remember deep details about things for years.

The discussions on this post have been the first time I've really hard people describe this phenomenon in such clarity. It's really nice to know there are other people who are similar to me in this way, as I very very often feel like the "odd one out" in this regard...