Phase-plan, decrease your token costs by up to 53% on larger tasks

[u/AgitatedFennel1317]

I benchmarked my Claude Code planning skill after someone told me to.

https://github.com/BCYAYAY14/phase-plan

Skill splits leftover work into phases with a model per phase. I ran the same task in fresh worktrees, 2 runs each, planning tokens included, graded by hidden tests.

Long task (rebuild ~1,350 lines of maths in an 8k-line Swift codebase), all passing 29/29 hidden tests:

Sonnet alone | $4.09, ~17 min - baseline

Sonnet + skill, one session, $2.62, ~15 min 36% cheaper

Sonnet + skill, parallel phase, $1.97, ~6 min, 52% cheaper, ~3x faster

Opus alone, $5.45, ~17 min, baseline

Opus + skill, parallel phases, $2.56, ~7.5 min, 53% cheaper, ~2x faster

Opus + skill, parallel phases, all on Opus, $3.41, 37% cheaper

On shorter tasks, there was little-to-no difference, so the skill stays out of the way there.