Q: Why do some keys sharpen "E" and flatten "C" when both of those notes are just "F" and "B". Particularly since those notes don't have an actual sharp or flat? Why kind of bullshit is that?
A: it's really just to make it work on the staff, because a key signature has to set you up so you have 1 of each letter. otherwise the key of F# would have 2 F's at the same time (F and F#) or the key of Gb (same key actually) would have 2 B's (B and Bb) and it would be a disaster on the staff, you would have to keep flattening and unflattening the B even just to write like a normal Gb major melody. it's really just to make the scale work with all the letters in a row. that's the point of key signatures. it's like 7 people with names A thru G have to represent the scale by holding up sharp/flat signs (or no sign). if you were not allowed to use E#, then the only way to make the key of F# would be to clone Frannie and kill Eddie