There's No Limit to How Bad Code Can Get

Blog · Watch/Read · (gathered 2026-09-10)

• Simon Willison argues that attempting to rewrite an old system from scratch to escape overwhelming technical debt (the “burn it down” approach) rarely works and often leads to a worse outcome.
• He details how this often results in “TWO systems in production”: the original, still-critical but neglected “moving target,” and a new, ambitious but incomplete system that fails to fully replace the old one due to underestimated scope and changing priorities.
• Instead of succumbing to the “siren call of a greenfield replacement,” Willison strongly recommends shoring up the existing system with extensive automated testing and then performing targeted refactors, citing Will Larson’s “Migrations: the sole scalable fix to tech debt” as a valuable resource.