Gain staging

Reading the manual, and I see:

“Turn up Gain so that the average loud signal reads
into the yellow of the meter. Turn down if any red peak
light flashes.”

dBFS Alignment +18dBu = 0dBFS (+22dBu at XLR output)
Meter Calibration 0dB meter = -18dBFS (+4dBu at XLR out)

Seems like periodically hitting the yellow would be like -22-30dBFS or am I reading this wrong? Not in front of mine right now, but wondering if peaks would be low in the DAW?

In several location recordings I’ve done I’ve found levels are always too low. I’ve had to go in and raise all direct outs. And still have to increase gain in mixing. I’m assuming their intent was to have a lot of headroom.

Even at -18dBFS there are still more than 16bits depth available.

The guidance is probably intended for live performance, where headroom to avoid clipping is essential.
In a studio you can just ‘go again’ if you clip, so you can afford to run much hotter, and get a much reduced noise floor - useful for postproduction.