Phals in general like to be more evenly moist-not soggy wet, but not completely dried out. They don't specifically need a dry rest in winter. Yes, if it is colder you will water less because it takes longer to for the plants to dry out. However, every person's conditions are different so there is no exact amount of water or frequency of watering we can give you. The best thing is to check the potting medium for moisture and when the medium is approaching dryness, then water again.
I don't grow Dendrobiums, so will leave that topic to someone who does.