Stirring butter toffee mixture while cooking When making toffee (equal parts sugar and butter, half-pinch of salt, water, vanilla) is it necessary to continually stir the mixture after it comes to a boil and the sugar has completely mixed in with the butter?

If it is not necessary, is it also not recommended?  Or does it matter one way or the other?
I'm not sure it matters that much.  In melting sugar for various candies, the reason for not stirring is so that you don't inadvertently cause the sugar to recrystalize.  For toffee, that isn't a concern.  I'd stir it at least enough to ensure it won't scorch, and not worry about it otherwise.