Thinking of moving over to Mx Pro Mac Mini. Use case mostly music production and general use (web, docs, video). I understand some/most use an external HD to supplement the internal. How does one judge how large their internal drive should be ? How much is left after OS, ect ? When installing software such as say Studio One or Logic Pro what has to be on the internal and what can go to the external ? Obviously samples, midi files, audio files and such can be installed on the external, but what 'has to be' on the internal drive to function properly ?