That would make me want to lower the spoke count until the tension needs occasional adjustment, which then begs the question of how to determine the need for adjustment?

When it comes down to it I guess the purpose of trueness is primarily to accommodate the brakes whereas the purpose of even tension is to make the wheel stable/robust to punishment and the problem is that extreme circumstances (such as very high tensions required for lower spoke counts) magnify imperfections and pit these two goals against each other.

So I guess the best technique is to make the tension as even and as high as possible without making the wheel so untrue as to compromise brake operation; And in my experience if you do this you will reach unacceptable levels of trueness before differences in tension become fine enough to require the superior accuracy of a tension meter (versus the pluck test).

Therefore, I propose the following algorithm for wheel maintenance:
1. Pluck spokes to check tension.
2. Tighten looser spokes.
3. Stop when either tension is equalized or brake interference is observed.
By never loosening spokes overall tension will be maximized and brake interference will become the stopping criterion, thus superseding a tension meter.