-CB- said:Keep in mind - the person in that video above is not really... doing things as they need to be done.
#1. Checking the relief at fret 12. Usually, its done at a fret midway (in distance) between the first and last fret. About fret 8 on a Fender neck. You don't use the "last fret" on all necks either. On many (most?) acoustics, its fret #1 and the fret where the neck joins the body. This is because acoustics have a fretboard overhang that has no adjustment at all (and is a source of @#$@# pain in older guitars).
#2. Having (and I quote the video) "a millimeter or two" at fret 12 is absolutely too much relief. That would be from .039 (1mm) to .078 (2mm), which would be .040 to about .080 at fret 8. TOTALLY too much. You want (depending on your playing aggressiveness) about .010, or the thickness of your high E. HINT: take a snippet of high E string and use it as a gauge (doh!). Capo fret 1, not too tight, then depress fret 20, 21, 22 whatever, and pass the "gauge" under the low E at fret 8. Adjust accordingly.
'Sorry, I didn't watch the whole video. That's not the way I do the adjustment. I also don't use feeler gauges. It's a "feel" thing, and I am very good at it...