As a CA, I fully support the FO reading the supp procedure and methodically doing the bleeds off procedure.
As a CA with thousands of hours on the plane now, I also now the gist of it is the APU will supply only the left pack for takeoff.
I know that means both engine bleeds off, APU bleed on, Packs in Auto, and xflow closed. Duct pressure, I expect the R needle to be 0 and the L needle to be at a normal value which is not zero. Auto, close, auto at the top. Off, on, off at the bottom, And verify R needle at 0, L needle has duct pressure.
Don't know why that's hard. I also see people looking at switch positions only, and not really glancing at the duct pressure gauge - which really is the true measure of verifying what you meant to do.
Once in the air, it's reverse C to fix it. Right bleed goes on. You get R duct pressure to come up (that's your verify stage). APU bleed off, you'll see L duct needle go towards 0, then left bleed on. L duct pressure goes up to a nominal value. At the top, Auto/Auto/Auto. And once done, verify both duct needles are at normal values, NOT at zero. If either of the duct pressures are at 0, you messed something up.