I once heard someone say that all contracts can be defeated by a club lead.
One thing that Bird and Anthias note is that after a sound NT contract is reached, although it is true that some leads are better than others, the difference is not great: Sometimes only 1-2%.
I also try to use the underlying principles that are suggested from the findings of Bird and Anthias but the proportion of the variance that their findings account for doesn't make them strong laws.
More like reasonable excuses when things go wrong.