Its a top of the board troubleshooter vs bottom of the board troubleshooter thing. I can look at a chip and poke a scope probe on pin 7 almost by reflex from the top but from the bottom (aka flipped chip) I guarantee I'll solder at least one chip "flipped".
I'm enough of an old timer that I'm still used to thru-hole enough that flipping a chip doesn't totally mess me up. I would imagine "kids these days" who never worked a thru hole PCB will likely be rather confused about where pin 1 appears when a chip (or board) is flipped....
Of course your fine tip sharpie pen is handy for numbering pins and preventing OCD cycles (Is that flipped over chip an opamp or a microcontroller? You can't see after its glued down, ya know). And lack of scribble on the groundplane is yet another example of this being project being fine workmanship. He doesn't even have stuff like +12V or LSB/MSB marked which is impressive.
I'm enough of an old timer that I'm still used to thru-hole enough that flipping a chip doesn't totally mess me up. I would imagine "kids these days" who never worked a thru hole PCB will likely be rather confused about where pin 1 appears when a chip (or board) is flipped....
Of course your fine tip sharpie pen is handy for numbering pins and preventing OCD cycles (Is that flipped over chip an opamp or a microcontroller? You can't see after its glued down, ya know). And lack of scribble on the groundplane is yet another example of this being project being fine workmanship. He doesn't even have stuff like +12V or LSB/MSB marked which is impressive.