230 files is hardly "all files of a filesystem", and if you run [ 2 or 3 times per file it becomes even slower. Many scripts are little more than glorified for-

230 files is hardly "all files of a filesystem", and if you run [ 2 or 3 times per file it becomes even slower. Many scripts are little more than glorified for-loops, and "run this on a bunch of files" in particular is a major use case of shell scripts, which is also why we have find -print0, find -exec{} \+, etc. It's up to you whether half a second is "fast enough" (just an example: can easily also be 2 seconds, or 5 seconds), but it's definitely a lot slower than 9ms and not "only much faster in theory", or "unnoticeable in practice", and "number crunching" doesn't come in to play regardless. Since the cost of this optimisation is minimal (you can just use the source of /bin/[ as a builtin) I don't see why anyone would choose half a second over 9ms.