One of my favorite shortcuts over the past few years -- I'm designing and my rehearsal notes say things like "Q21.5 earlier", and "Q17 T+2", or "Q202 on gunshot". After rehearsal I sit with the SM and go through my notes. I call out the correction and we both flip back and forth and back and forth to find the Q in the script to make the appropriate changes. Now all of my Q numbers are the same as the page number in the script (with point Q's as needed). So your Q sequence comes out "Q3, Q3.2, Q3.3, Q3.7, Q17, Q34" etc. Will it work for that musical with 75 Q's per song? Probably not. Does it always come out perfectly? No,
but it does considerably speed up notes after rehearsal. And on the light board, the Q numbers don't matter.