Documenting what you're willing to support (and not) (via) Devious company culture hack from Rachel Kroll:
At some point, I realized that if I wrote a wiki page and documented the things that we were willing to support, I could wait about six months and then it would be like it had always been there. Enough people went through the revolving doors of that place such that six months' worth of employee turnover was sufficient to make it look like a whole other company. All I had to do was write it, wait a bit, then start citing it when needed.
You can have an unreasonable amount of influence by being the person who writes stuff down.
This reminded me of Charity Majors' Golden Path process.