Disagree on the 'parallel arm tube' method.
You can disagree all you want but this is the method which in some cases renders best results with the least amount of headache. For example, the Lyra Delos is manufactured to sound best (i.e., achieve the desirable SRA) with the tonearm parallel to the record surface and then tracking at 1.75 grams. I followed Jon Carr's instructions to that effect and have been enjoying the music since day one.
I use a 30x magnifier, and my 'Littlelight' as a backlight, to initially set the SRA as closely as I can to 0 degrees (at 90 degrees to the record). I usually find that slightly raising the back of the arm provides the best sound, but my VPI 12.5 arm (like your 10.5) makes it easy to document repeatable settings.
M. Fremer wrote a very interesting and informative article in the June 2010 issue of Stereophile discussing SRA, VTA and VTF. Apparently the most optimal SRA is actually 92 degrees, not 90. He did, however, recommend starting with an SRA of 90 degrees, to be fair. Another critical consideration is the fact that getting that perfect 92 degree SRA is very, very tricky. I doubt a 30x magnifier is enough to determine whether you did in fact set it to 92 degrees (he recommends a digital USB-based microscope). Why? Because what matters is not the angle of the stylus SHANK, but the CONTACT AREA. You need to know your stylus profile's contact patch to get it right. In some cases, "the shank might have to be pitched far forward in order for the CONTACT AREA's SRA to be at 92 degrees."
I do agree, though, about making your settings on an 'average' thickness LP, finding a sweet spot, and then just playing some music-setting VTA for all records is way, way beyond my fussiness threshold, and borders on putting a premium on hi-fi effects, not on the music. IMO, of course.
We're in total agreement on this philosophy.