It's lovely seeing posts on social media (and, yes, here) from people who discovered Goetia last week and who have now, in their great experience and wisdom, embraced a grimoire purist attitude because anything else would be "ineffective" or "dangerous" or (gasp) "all in my head." It's equally wonderful to read smug responses to that from the opposite extreme: "I do it all in my astral temple, bro. I'm beyond tools and rules."
It seems to me that both of these extremes are similar and originate in insecurity. The first guy is terrified that he's going to make a mistake. Maybe an even deeper underlying fear is that none of it is real and he'll never know if he's deluding himself unless he follows a strict rule set, which is the closest he believes he can come to an objective success-failure standard.
The second guy is also afraid he's going to make a mistake, but he believes following the grimoire purist approach is only for rich people with degrees in metallurgy and their own towers. Since he, like most people, got into magic because he wants things he doesn't have (especially that tower), he circumvents his horrific doubts by making everything take place in his imagination.
There are many subtle gradations between these extremes, but stick around on this website (and on some of the ceremonial magic groups on FB) and you'll notice the grimoire insecurity before long. It's how Dr. Lisiewski and Steve Savedow marketed their Goetia methods. They sold a lot of books by exploiting the purist urge with horror stories from their own UPG (Savedow, in particular, reads like Book of Revelations fan fiction). There are also a bunch of Llewellyn and Weiser joksters who put books out in the other direction, some including a "Cicero method of magical tool creation," but tending seriously towards the all-in-the-head approach.
I'm writing this not to say that purist approach or the all-in-the-head approach can't work. What works for you may not work for someone else and there are some excellent purists who have a great, beautiful, grimoire practice. The opposite is probably also true, though harder to convincingly document because it's so subjective (cf. "transvocation").
But the insecurity, the angst, the defensiveness, the uncertainty is always easy to spot and that is what I'm inveighing against. It is often harder to keep an open mind, to say "maybe," than it is to get red-faced and loud about your pet method of reassuring yourself that magic isn't a waste of time.