MrBeast spends $5 million on a video and cringes when he rewatches it six months later. The diagnostic he uses built a $5 billion company in 12 years. Watch your own work from six months ago. Count the flaws. If the number is small, you've stopped compounding. That's the test. Most creators ship a viral video, rewatch it six months later, feel proud, and quietly plateau. The number gets framed as the ceiling. Every future video calibrates against the one that worked. Retention starts shaping…