Sure, it can help, but your friend needs to clean up his drive.
I like
OmniDiskSweeper. It will provide a sorted list of what's consuming your space.
If you run it with sudo (As shown below), it will include some system files that it woud not normally have access to scan. That is a more accurate representation of what's consuming your drive.
Code:
sudo /Applications/OmniDiskSweeper.app/Contents/MacOS/OmniDiskSweeper
Another option is to use this terminal command
sudo du -d 1 -x -c -g /
I prefer to redirect it to a text file (this puts it in your Documents folder
sudo du -d 1 -x -c -g / > ~/Documents/du.txt
Like the sudo /Applications/OmniDiskSweeper.app/Contents/MacOS/OmniDiskSweeper command, it will scan all directories, but produce a text file as opposed to showing the results in a window
I would highly recommend that your friend first ensure he has a current backup before doing any deletes, all too often we here about people cleaning up their drive and being a bit overzealous and removing stuff they regret.