For anyone who is self taught and only know about tab, here is a quick lesson. Manuscript is the lines that traditional methods of learning use to organize musical arrangements. It has notes, chords, and other neat things arranged in symbols in certain positions rather than with numbers. If you don't know anything about manuscript, you will be very lost if you continue reading this article. You have been warned.
- Double sharps/flats.
Double flats and double sharps are exactly what they suggest, two flats or two sharps stacked together. Their rarity is due to the fact that each of them would have an in-scale en-harmonic. For example, Bbb is also known as A, Bx is also known as C#/Db, etc. They are rare, but you may run into them once or twice in a lifetime.
2. Notes expanding into the 7 string guitar range
A seven string guitar is rare to find in bands, but as more metal innovators have existed it had to be created at some point so that tuning down would finally have an end. It is simply a six string electric with an additional B string as the bass note. When reading guitar-arranged manuscript, or a 5 string bass guitar (same concept, BEADG) for that matter, it is extremely uncommon to find music arranged for these instruments. Just like the double sharps/flats, this is probably due to their rare necessity as many people would rather read tab over ledger lines.
3. Large amounts of scale changes.
I'm not saying that a time signature change or change of scale is a bad thing for a song. I'm just saying that if you compose something and you change it three or four times for one verse/chorus/etc. that you probably need to find better ways to write music that will sound like you know what scales are. It is uncommon to see more than one scales change mainly because most rock musicians use a scale like B and then use the chords that go with D scale and only stay in the scale of B for licks and solos. Plus, it isn't like any pop music every gets that diverse.
4. Large amounts of diverse chords
This is just something you don't see in music period, but most people avoid writing out music that has a large amount of different chords. For those who can read it, congrats, but most of us common people have trouble recognizing a large amount of chords at first glance, especially when it comes to being barred seventh, minor, etc.
5. Large amounts of people who can ACTUALLY READ IT
How many people do you know who can tried and true read clefs. Look -tablature websites are great for learning a song quickly, but knowing how to read and understand music and the theory behind is just as important as knowing how to play it. My personal lesson -learn it because the amount of people who need skilled musicians who can read increases as few people learn it. Who knows, maybe you'll get a gig in music because you know how to read better then everyone else.