All of the above in my case. I realised a while back that I’m missing some fundamentals due to having come into the industry via being self taught. To deal with

All of the above in my case. I realised a while back that I’m missing some fundamentals due to having come into the industry via being self taught. To deal with that I’m currently working through NAND to Tetris, to get a grounding in how CPUs, compilers, and VMs work. After that I’ll probably find a good book on algorithms to work through, and then maybe (if I’m feeling adventurous) attempt an OS myself.