Sometimes, I have to install a local .deb package. When doing so, it happens that I miss some required dependencies.
When using dpkg -i mypackage.deb, it fails for each missing dependency, making it a tedious task to install each of them.
I just found out that apt is capable of installing a local package with its dependencies, when doing apt install:
sudo apt install ./package.deb
EDIT: You don't actually need --fix-broken