I've played guitar left-handed for over two decades. Every diagram, tutorial, and scale chart out there is drawn for a right-handed player — so you spend half your practice time flipping things around in your head.
That frustration is exactly why I built SouthpawStrings.com: tools with the left-handed fretboard as the default, not a toggle buried in settings. Right-handed players are welcome too — everything works just as well flipped the other way.