New Drizzle versions: Foggy procedure ?

Lets try to clear the fog away once and for all times.
So far, I have always made a new installation when a new Drizzle version was published.
Question: is a new installation (Drizzle over Uru CC, MOUL and Myst 5) really necessary or can we just update our older installation ? EDIT: have added Uru CC
If only an update is sufficient, are there proper detailed procedures/instructions on how to proceed ?
Thanks Nanouk.
So far, I have always made a new installation when a new Drizzle version was published.
Question: is a new installation (Drizzle over Uru CC, MOUL and Myst 5) really necessary or can we just update our older installation ? EDIT: have added Uru CC
If only an update is sufficient, are there proper detailed procedures/instructions on how to proceed ?
Thanks Nanouk.