I have never “top dressed” any orchid pot. In my experience it messes with the normal wet dry cycle of orchid culture.
If my plants dry out too fast, I a. Water more often or b. I increase humidity c. Or if an orchid needs more water I put it into a finer mix.
Conversely if the plants dry out to slowly I decrease water frequency or I increase air movement.
If you pot it correctly and use the appropriate media, there should be no need to top dress. I know florists do it because the orchids that they sell might look “prettier.” I don’t want prettier, I want healthier.
If an orchid stays to wet, try growing it mounted.