Valve clearances

I’ve always set my 850GT loop valve clearances to the factory manual - 0.25mm exhaust and 0.15mm inlet. The factory book that came with my Spada shows both inlet and exhaust should be 0.22mm, as does my Haynes manual for the Tonti frame bikes.

Does anyone know if the loops are different for a reason, and if it’s a good idea to adopt the later clearances in the earlier engines?