Max reasoning is not always the right answer.
Right answers on a 50-step calculation
Right answers on two 300-step calculations
Right answers on 14 level-10 questions
More effort helps on some tasks and wastes tokens on others.
On a 50-step calculation, max, high and medium effort all got it right, but max used 24,875 tokens, against 8,932 for high and 7,584 for medium. On two 300-step calculations, high effort solved both, while max kept reasoning past the 128,000 tokens one reply can hold and gave no answer.
More effort can also pay off. Raising GPT-5.5 from low to high effort took it from 7 to 12 right out of 14 level-10 questions.
What it means for you. Use higher effort where it gets more answers right, not by default. On everyday work it can cost several times more for the same answer, so test effort settings on your own questions. Read finding 2 → Read finding 7 →
Tested: Claude Opus 5.5 · max effort: October 8–15 · high and medium: October 15 · GPT-5.5: Codex (0.154.0), October 4, 2026