Notes on not getting hired

On a whim, I applied to a defense tech company. Their recruiter emailed me three hours later. We had a phone screen the next day. A coding interview the week after. A second coding interview the week after that. Just like that I was in a final loop. One application, no networking, no LinkedIn DMs, no referral. I nailed the coding portion. Had a genuinely good conversation with the hiring manager. Then came the system design round. I had never done a system design interview before. I walked through an architecture and started second-guessing myself out loud. It's exactly as bad as it sounds. You can feel the moment an interview turns. It's like a key that doesn't quite catch. You keep turning it, hoping it'll grab, and it never does. I had no idea what I was doing, and worse, I was demonstrating that fact in real time to several strangers. The recruiter called with a rejection two days later. At least it wasn't an automated email. 1 application. 1 final loop. 0 offers. 75 applications w