When a portion of music, say 16 bars from the start, has a repeat sign at the end of that 16th bar, the direction means go back and start again. The sign I mean is II: at the beginning. So why do some pieces have a reverse repeat sign at the beginning. There's nowhere else to go back to, it seems pointless. Why is it featured in some music?
Are you talking about something like this? This is a excerpt from “The Latin Real Book” by Sher Publishing.
I learned a backward repeat goes back to the top if there is no forward repeat and I agree it is not necessary but then again I have seen dozens of published pieces and professionally copied charts written with and without the starting repeat at the top. I’m guessing someone decided to do it x years ago, maybe for the sake of clarity and it caught on.
It doesn’t bother me personally because if I’m sight reading I start with the knowledge that I will be returning to the top of the piece.
It might just be for consistency, because that is how one would usually enclose repeats. Also, it doesn’t hurt to make things unambiguous, even though it’s not really necessary, sort of like a courtesy accidental, perhaps.
Also, sometimes there is an anacrusis right before the reverse repeat sign, in which case you would not repeat the anacrusis; but I don’t think this is what you were talking about.
Edit: I don't know much about the use of courtesy/cautionary accidentals, so maybe I shouldn't have made that comparison. Anyways, the point I was trying to make was that being unambiguous doesn't hurt.