I love Toba Garret's Royal Icing recipe from her book "The Well Decorated Cake"to make the flood icing by adding 1-2 ounces of water to the royal icing a little at a time and stirring it carefully with a spatula. After you add half of the water check the consistency. Continue to add water until you have the flow consistency.
Her book says, you have achieved the flow consistency, after you run a knife through the icing, the icing completely comes back together after you count to 10 seconds. If the icing comes together before 7 seconds, add a little more royal icing to thicken it.
I use it for my cookie bouquets all the time. I took me awhile to achieve a smooth cookie without air bubbles. I learned from trail and error not to use the whip blade either, and I definitely don't use squeeze bottles, because just the action of adding the flood icing to the bottle created a lot of air bubbles. I out line the cookie with stiff royal icing, then flood and use a tooth pick to bring it to the edge and give the cookie a gentle shake to make it all uniform.
There are all sorts of wonderful recipes for royal icing, but this one works for me. I like that it comes out so fluffy, smooth, and light, and I don't have to struggle with it when doing pipe work, because my wrist are shot,lol. I plan on using it for Valentina's Day cookie bouquets.