It can also be annoying when a script changes directory itself. If anything the script does is relative to the current directory (interpreting a relative path,

It can also be annoying when a script changes directory itself. If anything the script does is relative to the current directory (interpreting a relative path, creating output files), you now can't have that be relative to your current working directory. Best practice, IMHO, is usually for scripts not to touch the current directory, and to be agnostic to it.