The problem is that the subject of ceremonial magic is such a sprawlingly complex one that it's very hard to determine accurately who did what and how you should do it in future. If you go back to the older grimoires, even the most egregiously self-aggrandising rituals are backed up with appeals to God and the Archangels and use the right-hand-path formulae. Nobody generally likes to put their hand up and go "I'm evil, me!" especially not in an era where the rack and the stake awaited you if you got done for it; so doctrine on Black Magic practice is skimpy and messy to say the least. Meanwhile, most modern grimoires draw heavily on the author's imagination rather than on the older texts. It's damnably hard to piece together a logical, unbroken chain of development for ceremonial magic, so the rule these days tends to be "do it how you think it should be done."

So in summary, yes, you can go widdershins if you want to, but not everyone would. :)

My impression from modern "white" texts is that the direction of rotation affects the accumulation of power indiscriminately.