[sdiy] PTH vias

[Seb Francis]

Hi,

Does anyone know whether it's a bad idea to cover PTH vias with solder 
resist?  By default my PCB software leaves a gap in the solder resist 
which means that you can't place silkscreen legend on top of a via.

Looking at some commercial PCBs I see that quite often vias are not 
covered with solder resist.  Is there an electrical reason for this?

Nowadays my PCBs are Immersion Silver finish (which is a 1 micron thick 
plating of silver on the copper) if that makes a difference?

TIA,
Seb