Hi,
totally agree with Taniwha. You can't wait long enough with yacht/spar, i cure my varnished bamboos hanging in a tubular oven over a 75 watt breeding lamp for 4 days before adding a next coat (6 in total)

! When using epoxy it all goes a lot quicker and if you get the hang of it you can varnish rod wrappings beautifully with one thick single coating (provided you keep on turning the rod for a couple of hours!). In general, regardless of the type you are using, the longer you wait between coatings the more it becomes important to sand the previous layer lightly with 600 to 800 sandpaper making it more receptive of the next coating to avoid splitting or flaking of one or more layers.
Have fun building and fishing your rod!
Johan