$20 is fine. I used a free trial before Christmas, and my experience was essentially that my code review speed would've prevented me doing more than twice that anyway… and that's without a full time job, so if I was working full time, I'd only have enough free time to review $20/month of Claude's output.

You can vibe code, i.e. no code review, but this builds up technical debt. Think of it as a junior who is doing one sprint's worth of work every 24 hours of wall-clock time when considering how much debt and how fast it will build up.