Yes, you can leave other numbers out apart from #19 open by moving the chips while respecting the proportionality.
For instance, using HIGH for the even chance and the 1ST DOZEN for the outside and moving the corner and straight-up bet to the 13/18 double-street inside.
You can target the numbers in the splits: 13/16 15/18 19/22 21/24. Perhaps if one of them shows "enough times" (x4, x5... to your personal criterion) while you are betting and you want to try your once-in-a-lifetime shot!
For instance, using HIGH for the even chance and the 1ST DOZEN for the outside and moving the corner and straight-up bet to the 13/18 double-street inside.
You can target the numbers in the splits: 13/16 15/18 19/22 21/24. Perhaps if one of them shows "enough times" (x4, x5... to your personal criterion) while you are betting and you want to try your once-in-a-lifetime shot!