@JosephWright I guess, you have seen
tex.stackexchange.com/a/261924 Maybe it would be nice to have a new feature: SIrange should check wether it should result in two different unis like here or if not. Normally, I have
range-units=single
loaded. Would be cool to get 3 to 5 Hz but 3 Hz to 5 kHz if the case of that post applies