My Studio One Professional 5.3.0 DAW displays tempi to 2 decimal places. Using the ‘irrational WRT MIDI’ tempo of 66 here is what we have:
Two decimal places is surely adequate, isn’t it? I do not deny the need for fractional tempos but I still claim 4 decimal places is misleading with its supposed level of accuracy, even if arithmetically correct. As far as I know Studio One is used by thousands of industry professionals and so far I have not heard complaints on forums that two decimal places of accuracy is inadequate.