What wasn't working
A lost model is not a few hours of typing: it is a project, sometimes months of a practice's work. The question was never how fast the disk was — it was always how much work is at stake the day that disk stops.
A building model is not an office file: several people open it at once, it grows with every revision, and it has to answer in seconds. When the server drags, it isn't one workstation waiting, it's the whole practice.