Bass and treble clefs are different because they need to cover different ranges. Likewise with alto and tenor clefs, the other two you see most often in modern

Bass and treble clefs are different because they need to cover different ranges. Likewise with alto and tenor clefs, the other two you see most often in modern notation. Or baritone clef, great bass clef, soprano clef, French violin clef... it goes on and on. Actually the mass codification of treble and bass clefs is a problem, because people don't learn to adapt. Once you can read four or five clefs fluently, new ones are pretty easy to deal with. If you only ever learn one or two they all seem difficult. The "second number in the key signature" is actually in the time signature, and it's pretty important. Although we didn't always have it - some older music just says "3" and you have to figure out 3 whats by looking at the music. Or go earlier than that and you'd have a circle, a broken circle, or one of those with a line through it. And no bar lines. I think most musicians agree the current system is an improvement on these in general. But take modern convention, look at how we write out English traditional music and you'll see that the 3/4 or 3/2 distinction is quite important as the first one is a waltz and the second is a hornpipe. You might not care about that, but anybody trying to dance to that tune will. If it helps, intervals are named in a 1-based system not a 0-based system. They're called octaves because you go to the eighth note in the sequence, not because you add seven. And yes I know there are actually 12 notes in an octave in Western music, but you're usually operating in a key or mode that has picked out eight of them to be used in that moment, because that's how Western harmony works. Of course we can improve music notation, and we will - it is still changing. Composers need to write down things that haven't been written down before, so they come up with a way to represent it. If that thing catches on, the notation will become standardised. Time signatures, which you called out, have changed completely over the centuries. You used to get a circle, a broken circle, or one of those with a line through it. That was it. They'll probably change again when someone has a really good reason to do it. Even our conventions for what note values to use have changed. There's a reason the semibreve - a whole bar of 4/4 - has a name which means "half a short note". Yet many musicians today don't know what a breve or a long or a longa even look like, because there's been a shift towards using quavers, semiquavers, demisemiquavers and so forth. The whole US system for note naming kind of enforces that, with the idea of a semibreve being a "whole note" as if 4/4 is somehow special (it's not).