The Fusion implementation sucks. A spreadsheet is a far more natural way to do this, Im surprised FreeCad is doing it better than the paid variant.
The Fusion implementation is awful - you can adjust one variable, one time, then you have to reopen the dialog to do another. At least for me it's always become non-responsive after a single edit, for years now. I've always assumed I'm just holding it wrong, but I don't know. I've moved on.
The only issue I have with the Spreadsheet is that I need to add an alias for every value I want to use in the Sketch or Part Design workbench. In practice, this usually looks like
and for every cell in B I add an alias with the same value as in column A. Is there a way around that?