He made a guideline, not rules. If you don't think you're ready to move up then don't. If you're questioning it "take a shot" and just play until you've hit a stop loss (which may be up 8, down 10 BI who knows).

I still do this being "overrolled" for the next level because it's necessary for my mental health (as it relates to poker). If I'm not comfortable and drop a couple buy-ins (even if I'm up overall) I drop down and get my head straight.