Does restaining a deck (rails only) require you to strip off the old stain?

I put Rhino Deck on the floor of my deck. The railings and steps are treated lumber. My question is once I stain can I put a polyurethane on to finish? And is there any advantage to do this?

Used “Thompson Water Sealer” clear. Went on in spots darker even after drying. Why if it is supposed to be clear and show the underlying wood colour?

I stripped the deck that had a semi-transparent oil base stain using stripper and high pressure and in a few spots a wire brush. I rinsed with high pressure and the next day with garden hose. It rained on it the next day. The deck set for 3 days with

If one was to spray a deck using oil base instead of brushing does it make a difference in the quality?

I had my 1 yr old treated lumber deck stained with oil based stain 2 months ago–Sap is bubbling through the boards and the stain looks horrible. It was 90 degrees when they did it. How can I repair.

How to remove a Thompson’s deck wood stain that is peeling?

Does a new wood deck have to be power washed?

There was high humidity when stain was put on. Some areas are dry other areas look shiny and are tacky. Can I take turpentine on a rag and wipe over shiny areas to absorb the excess stain that is tacky to speed up drying?

I recently powerwashed my wood deck and now have small feather-like wood fibers everywhere. Is this a result of being too aggressive with the powerwasher or is it normal? The deck is about two years old and had never had kind of treatment whatsoever. Should I go back over the