In my experience, this usually manifests itself as a bash script, though any untested/untestable “script” can exhibit this pattern. The script’s complexity surpasses a point where manual testing or limited end-to-end tests can prevent issues – and so, breakages will happen. There will be pushback against the rewrite: the rewritten script needs to be feature compatible with the old system; the rewritten script needs to be released safely; rewriting the script will consume valuable developer time that could be spent working on Shiny New Features.