As long as the function of the script is clear, I don't see any reason why it should be limited to any particular size at all. If your script is 5000 lines, so

As long as the function of the script is clear, I don't see any reason why it should be limited to any particular size at all. If your script is 5000 lines, so be it. On the other hand, it would probably make sense to break that script into module-sized smaller scripts. The 'base' script would call those 'module' scripts as and when necessary. Then each 'module' could be debugged and/or modified separately.