It is unnecessary, in this three in a bar, to mark all the quavers; the rhythm of a crotchet followed by a quaver in each beat suffices.
As to the subdivision, the little supplementary gesture for simple times should be made; this subdivision will however separate each beat into two unequal portions, since it is requisite to indicate visibly the value of the crotchet, and that of the quaver.
If the movement is still slower, there can be no hesitation; the only way to ensure unity of execution is to beat all the quavers, whatever be the nature of the written bar.
Taking the three measures shown above in order, the conductor must beat three quavers down, and three up, for the time of 6⁄8:—
Three down, three to the right, and three up, for the time of 9⁄8:—