Claude code has aggressive limits on $18/month plan. You can get much farther with Minimax 2.1 or Qwen3 on the same amount of money. I have noticed opus is much better in some scenarios but Minimax and Q3 are not as bad or behind. Or my setup is now too used to the quirks of those models, who knows. I am using Claude Haiku as small model anyway, just not using Opus because it burns credits very quickly.