My personal opinion is that if your string size is like the Dimension Strings setup, 8-8-6-6-4, then you shouldn't need woodwinds in groups of three (except for special solo passages for something like an alto flute...).
But if you are using a larger string ensemble, like 20-16-10-10-8, definitely make use of the a3 instruments. For example, if you have a melody in the flutes and 1st Violins and it is forte or louder, then I'd for sure use the flutes a3 patch for balance purposes. If it is a soft melody, use just 1 flute for strings that large.
For tutti sections, check out the final presto from Mahler's 5th Symphony (I attached a screenshot). For the last 6 pages, the flutes play a4, oboes a3, clarinets a3, and bassoons unison a2 with the contra playing an octave lower. Those groups double the string chords' top note. Notice Mahler doesn't try to fill out the chord, but because the brass is playing the melody, all unison, very loud, those woodwind chord notes would be totally lost. So, he just has all of the high winds play the top note of the dominate root--dominate root--tonic root. Plus, so it's not too soft beforehand, that wholetone scale is also in a3 unison.
Instances like that I would say are the main function of a3 VSL patches.