IME it's *rarely* needed. Normally aptitude safe-upgrade installs and removes packages as needed.
I beg to disagree. Here you speak about *aptitude* which is a tool that is not the plain apt tool itself. You could also say things for dselect, synaptic, discover...
With apt-get, you have to use dist-upgrade quite often because as other have pointed out, you cannot add or remove packages without dist-upgrade.
Clearly to install libkdecorations2-5v5, you will need apt-get dist-upgrade. And the libkdecorations2-5v5 that was wrongly put in experimental does break the unstable version...
-- eric