Vanda orchid suddenly loosing leaves

[jcec1]

I don't think it's watering frequency. I think it is cold and water collecting in the leaf joints. I lose a few leaves like that on my vandas each winter, but now the sun is getting a bit stronger and warmer it should dry out quicker. Mine are in vases just like yours and I find that watering once a week during the winter is sufficient, just try and get them dry as possible afterwards.