From what I understand, the value does vary, there is no fixed value to trade the news. I do not understand where one would start to determine whether to go short or long based upon a certain value being too low or high.
All depends how conservative you want to be with your triggers. The higher the deviation, the more impact it creates on the market. Triggers are there to help a trader guide him or her to either enter a trade or scratch it.
i think we have to be flexible with triggers. i my self always set a conservative triggers, but often to jump in to the market if the actual result is differ not much with my triggers.
