Old methods work, new methods have been developed because the old methods have some weaknesses, pros & cons and all that.

If you use a gage, make sure you treat it well and give it some light oil like triflow on a regular basis.
I use to work in a shop where I would hand true about 3000 new machine built wheels per year, from various makes and models. Tension gages were preferred to fiddling with old timey methods for both consistency and speed. On a good factory wheel this would take about 3-5 minutes, on a bad one(with a slightly warped rim and crazy off tension) maybe 15.

The basic process when using a gage was: stress the spokes, check dish, test a few spokes in a row for tension to get a basic tension starting point, if way off target give every spoke a quarter, half, or full turn(depending on the starting tension and dish. Treat every spoke on one side with the exact same amount of turns or you may screw the radial hop. Do not stop half way around to check tension, answer the phone, fight off a bee, or anything else.) note any spokes that feel like outliers double check them with the gage and load balance as necessary,
Stress again, check a few more spokes,
When tension is close, move on to truing, and true with balanced turns to avoid throwing off the radial or the tension. eg, if the spoke in the center of the wobble is on your right and needs to be about a half turn looser then take up the slack with 1/4-1/2 turn tighter on both adjacent spokes on your left. Small adjustments of about 1/4 total turns and less generally don't need balancing.

Stress again, check dish and true again, make fine adjustments, rinse&repeat as needed, ending with stress, check, done.

There was a direct correlation between turns and tension readings something like one full turn on each spoke would swing from 18-22 on the park gage, I don't recall the exact number as I haven't done it in about 2 years, it was not quite linear though, more turns were needed to adjust one point at very low tension than were needed at very high tension.