Furthermore, timestamp precision is still problematic. Some filesystems still have one second granularity, but even if you use a filesystems capable of storing

Furthermore, timestamp precision is still problematic. Some filesystems still have one second granularity, but even if you use a filesystems capable of storing sub-millisecond timrstamps, that doesn't mean commands that get invoked as part of the build process (e.g. cp -p) invoke the right APIs that make use of such precision. e.g. see the doc for the .LOW_RESOLUTION_TIME directive of GNU make