Wilton recipe says low for 7 to 11 min while Joy of Baking says med to high for 5-7....can anyone narrow it down for me?

I don't make it often enough to remember, but I don't think I used low speed before...

..moving to Recipe Tips & Ideas.

This fresh egg white Wilton R/I recipe recommends beating on high for 7-10 mins.:

http://www.wilton.com/recipe/Egg-White-Royal-Icing-1

The JoyofBaking recipe also uses fresh egg whites:

http://www.joyofbaking.com/RoyalIcing.html

The Wilton R/I recipe that recommends using different speeds is for use with meringue powder based R/I:

http://www.wilton.com/recipe/Royal-Icing

HTH

I always make my RI using meringue powder (CK brand). I have the KA Pro 600, so these #s are all for that.

I start on 2 mixing the meringue powder and water together. I stop the mixer frequently and scrape the bowl. I keep doing this until all the meringue powder is dissolved. Then I kick it up all the way until the meringue is formed. I turn it back down to 2 or 3 as I add the powdered sugar. Once all the PS is in and not going to fly up everywhere, I kick it back up to 8, stopping the mixer and scraping the bowl, sides, bottom, everywhere, two or times during the mixing process.

HTH!