I still find it easier to understand something if I understand it from the ground up instead of in an ad-hoc way. For example, I found it easier to reason about probability once I had seen a rigorous definition for what a probability distribution is. I guess the reason is that it gives me a way to sanity check my intuition.
I still struggle with the fact that in software development, you get hundreds of technologies thrown at you and you barely have any time to understand them all fully. It makes me sometimes feel not very confident in what I do. I feel that I could understand e.g. Kubernetes better, if I had real in-depth (not just superficial) knowledge about networking. A lot of the time I'm just missing crucial information like "what problem are we trying to solve?", "why does this technology work the way it works?", etc. Something like Kafka is another example.