Clients and agencies both love to take refuge in "best practices."
The general definition, at least when it comes to advertising, is that they're a method, technique, style or set of defined guidelines that've shown results in the past better than had they not been used. They're tried and true. They've worked before. They'll work again.
Which begs the question: how do you know?
The truth is best practices make both sides feel they're doing the right thing - the optimum that can be done. It provides acceptable and universally understood cover if the effort fails.
In reality, what they do is slam the door (or block the road - it was the better picture) on new ideas. "Best practices" is the quintessential synonym for "It's worked before, it'll work again."
The problem with that line of thinking is the same one dice have at the crap table: they don't care what the odds are. In other words, best practices are just that. Until they're not.
Next time someone asks if you're using best practices, tell them not a chance. If they ask why not, say it's your best practice against mediocre work.