The last consulting firm I worked for had over 70% of their revenue coming from two contracts, and neither contract used any of the tools or philosophies the consulting company claimed to espouse.
Ended up being the case that all the reasons I wanted to work there were just marketing messages and my sense of betrayal soured the relationship.
That the guy in charge of developers left about a year after we parted ways... every time I think about those people I wonder if he knew it was all bullshit or if he just got tired of dealing with attitude from stressed out developers and never understood why they were pushing back.
Assuming you're talking about philosophies that are considered good practice because they lead to more sustainable design practices and smoother development later, I have doubts those ever survive in long-term consulting contracts. The way pressure flows in those scenarios always leads towards emphasizing speed of development. Anything else requires multiple points in the management path both in the local firm and client firm to be willing to forego short term cost for potential long term gains, and if any one of them is out of alignment it causes problems.
> https://www.theguardian.com/business/2008/mar/27/wolfson.app...
Apple starts a relationship with a company, the deal becomes the VAST MAJORITY of the company's revenue, the company wants to get out of the buisness of being an apple supplier, because IF they scale to that size and lose a contract, they have huge cuts to make. So apple comes in, buys a substantial part of the company, and now the company can continue to operate without fear of downsizing. Any downsizing will be apples doing not theirs.