Funny you mention all this Myrna. Yeah, I agree: there is a certain formulaic approach Deva stylists have that has rubbed me the wrong way too at times.
You're so right about product overload. Cutting is their thing, but I think styling is not. Like you, my hair is always crisp when I leave lol. They love the product overload. And like you, I've brought my own products. Each time it's a pain in the ass because they say stuff like, "Oh, sure, no problem, but ... there's this product that I'd like to try on you instead." The last time this happened it was their HIH conditioner and after she'd worked it through my hair she said, "This is free because it's a complimentary treatment. Next time it will be ten dollars."
Also, when she found out I was using coconut oil as part of my regimen, she got all serious and told me how bad it is. I didn't bother arguing (she clearly didn't know an infrequent shampoo would remove any buildup). Just ignored her and changed the subject.
As for their practice of placing clips at the roots, unlike you I have to tell them not
to do it. I find clips to be unnecessary work. I figure, why fuss around with clips when all the stylist needs to do is cut a little more length off to create the desired spring/body?