your comment made me realize that my crooked valve comment most likely comes from having fixed other peoples bikes with really askew valves, maybe I once misplaced a tube in a tire and it wasnt straight, but I certainly have seen other peoples wheels with really askew valves really forcing the whole valve/tube area. These may have been situations where the tubes were too big for the tire and had been fudged in , folded over or whatever, who knows.
its funny, like fb said, there are many ways to skin a cat and I just have the habit of starting to work the bead in from the valve area and work away from there, finishing up wherever I finish, and don't really think about it.
Its such a mundane action that in the end, if whatever technique one uses works all the time, with direction, with levers etc then great.
its all a ritual aint it, I put baby powder on my tubes before putting them in, or when I put them in a plastic bag with my fixit stuff--does it really help a tube not stick to a tire over time, I dunno, but it does smell nice and now its part of my ritual, hail mary, something of grace....
Today I was tuning up a friend's MTB bike incl replacing tires/tubes & tried Working Toward Valve. The new tires were easy to mount w/o levers so Towards Valve didn't make much difference & actually on one tire that took an extra 2 minutes because the valve seemed like it was hindering beads next to it from seating easily. Perhaps on tight road tires technique becomes more crucial.
http://www.sheldonbrown.com/brandt/talcum.html
Jobst Brandt says talc is added by tube makers to keep tubes from getting stuck together from heat of manufacturing & gives no benefit otherwise incl when mounting:
Once had an on-road flat w/tight Specialized sport-touring tire & I couldn't remove it w/o levers for the life 'o me. Mechanic at the nearby LBS removed it w/o levers fairly quickly; he quickly showed me the technique but I didn't quite grasp the details. & it's similar with internet videos about working tires w/o levers--they're usually easier (ie MTB) tires and/or they gloss over exact steps.