We developed certain conventions in layout since starting inputting the iReal Pro tunes so they look, function and get interpreted quickly in the same way. Mainly the reason is ... once you get used to reading the charts, you get to easily understand what is intended—we came from a jazz perspective initially so we saw the app as being something you might have to use on a gig (perhaps without a rehearsal) so clarity and consistency were important to us.
Here are some rules we developed. Of course you do not have to adhere to them...