At the studio, we use the 8-point grid. That said, until there is a clear definition of the product and we know in what direction UI is going to go, there is no point in doing it.
It would disrupt rather than help.
Links of reference about the 8-point grid:
Intro to The 8-Point Grid System - Built to Adapt
8-Point Grid: Borders And Layouts - Built to Adapt
The grid is used for paddings, margins and spacing in general. It isn’t applied to font. The size of the font doesn’t necessarily have to be a multiple of 8.
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