@Sunil's comment about being stuck to a tempo
That doesnt include me mate - i gave my answers because someone asked, those are calculations i wrote C++ programs to achieve and work for the key's stated, mostly i dont use them because of sequencer issues but occasionally i do.
The figures i quoted and keys mean that the bass waves in those keys sit exactly on the quantise grid and the compression/refraction waves pump in time to the music thereby increasing the efficeincy of the waveform.
MOstly, like you said.. its whatever works.