Hey 2P,
We lose about 10 days per winter season, and they are always well known in advance, and when I spoke to them it was either Bern or Basle as the Div with Buchard doing the transfers - its certainly not a weekly thing, but nearly always between the 6-8th Feb one of those has been shut for the last 4 years, then off days or afternoons depending on snow / fog etc..... but like the rest of the world.. who knows anymore - sometimes we have all 4 seasons in a single day!