How widely accepted is the number 13 / capital letter B as an indicator of treasure?

[georgieb]

Hello! Newbie here. I happened upon a symbol carved in stone that looks like a capital B, but with slight gaps between the vertical line and the arcs of the B, making it look also like the number 13.
I have read in previous posts that this indicates treasure, but I'm wondering how widely accepted that is in the treasure hunting community?
The B/13 is framed by a box, with an arrow pointing down.

 

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