The best "gloss" factor is when you put clear right on top of the single stage.
Single stage is just colored clear. When you put Clear right on top of a already shiny single stage it realy gives more depth and gloss.
You can let the single stage dry and block it down with 600 and then re-clear. It will give a great finish too.
Your good to go either way. I've done both.
Just make sure the product you use will be able to be topcoated with clear after flash time.. (just like another coat of color) Most are ok with that.
I always like to read the tech sheets or ask a user of that product.