Yes contemporary classical scores require this. For example in Thomas Ade's Orchestral Suite from 'Powder Her Face in the Overture he has several 2 over 6 and 4 over 6 bars. While this is certainly pretty uncommon a regular 4 over 4 bar would be equivalent to 24 over 24 in relation to a 2 over 6 bar which would be 8 over 24 and a 4 over 6 bar would be 16 over 24. It would be good to see Notion be able to negotiate these types of rhythmic relationships. If I wanted to use Notion to create a metronome practice template in order to help work on this particular piece there is no way that I can see that the program currently can facilitate programming these particular measures.