I can remember noting that we were not following a large number of the best practices. In fact, what is more interesting is that we had made those decisions without considering the so called "best practices".
However we did not make those decisions without considering all the variables. In each instance where we diverted from the best practice we did so for good reason and with our eyes open. In other words, we did not deviate from best practices because we were rebellious but because we knew what we were doing. In all cases we had a ready defense for not using the best practice.
I realised in doing this that the point of best practices is to protect the person who does not quite understand what they're doing, to make sure they don't really shoot themselves in the foot. For those people who understand the situation, best practices are useful because they provide a base to work from. If you deviate from best practices make sure you can defend your deviance.
Furthermore, I'd also like to add, that very often a so called best practice is someone's opinion. A few months ago I wrote on what I thought were hibernate "best practices". These are based on my experience and my opinion, they are my best practices not necessarily industry tried and tested best practices. So the label "best practice" is often a fairly loose term.
Best practices are for people who don't know what they're doing, but for people that do, the tried and tested ones are a good and worthy starting point that should only be deviated from for good reason.