From "Growing Orchids in Your Garden
" by Robert Friend... "The most beneficial companion for a newly attached orchid is a drape of the so-called Spanish moss, which is the bromeliad Tillandsia usneoides. This most useful plant, which consists of a tangle of curly, mosslike strands, provides a humid, nurturing microclimate around the newly affixed orchid. It also provides a modicum of shade and wind protection when draped around the base of the plant from which new growths and roots will emerge." p 31-32
Strangely enough, Friend advises against using Sphagnum moss for mounted orchids. He feels that the roots will stay in the moist Sphagnum moss and not attach to the tree. Also, he feels the Sphagnum moss can potentially hide pests.
Bare root orchids in baskets are pretty much the same as bare root mounted orchids so Friend would probably also advise draping Spanish moss over Vandas in baskets.
A while ago I visited a professional orchid grower and he gave me a tour of his greenhouses. In one of his greenhouses he had dozens of flourishing Vandas in baskets with generous amounts of Spanish moss wrapped around the basket and roots. I asked him about it and he said he really struggled trying to get Vandas to grow until he started wrapping the Spanish moss around their roots.
Personally, I think it depends a lot on your growing conditions. Humidity and moisture is a greater concern here in the Los Angeles area compared to Florida. Although, I'm sure the humidity and moisture levels were pretty high in that orchid grower's greenhouse. Protection from winds that dry out exposed root orchids is another factor as well.
I think that if your Vandas are doing fine then I would leave well enough alone. If you feel that they are getting too much moisture then you might experiment watering them only 3 or 4 times per week and see how they respond.