me too.
1-4 don’t exist basically because you can’t hear it. 5 is the lowest it can be otherwise it’s off. 5 is used when you want it on in case a good tune comes on and then you can turn it up, but it is not a listening volume.
6 is pointless because it’s same as 5, can’t have 7 for obvious reasons so 8 is feasible but by the time you get to 8 you may as well have 10.
After 10; 12 is acceptable, a bit louder than 10 but then 14 isn’t because you may as well have 15. Likewise 16. So 18’s the next potential and even then, by the time you get to 18 you may as well have 20 which is getting to be too loud for when others are in the car, it’s for furious speed driving making progress, but within the speed limit obviously.
And then for really loud music, 25. It does go up to 30 but then the speakers distort and you can’t hear it properly anyway.
So there you have it. 30 volume settings of which 5, 10, 12, 15, 20 and 25 are the only acceptable ones. And in the interests of symmetry, I’m trying to do away with 12 too (but sadly that’s the perfect number for loud enough to hear but also have a conversation with passengers)