I usually aim for ft spoke tension somewhat between the two sides of a typical rear wheel (that has rather off set flange to center of axle ends due to the many cogs on one side. A flip flop will have much less offset and thus less tension difference).

I will take some issue with the mechanic who placed trueness over tension. Both are nice to have proper but I would place a higher value of evenness of tension then absolute trueness. A consistently tensioned wheel will tend to be more stable and reliable over the miles then one that initially looks straighter but has some spokes fatiguing faster then others. Andy