“Holding the breath gives us a moment when there is nothing happening.
A moment when it should be possible to count.
In fact, the best time to introduce Mantra is not during inhalation or exhalation but while holding the breath.
It is said that a moment of holding the breath is a moment of Dhyāna.
Some Mantra are very long.
Since we do not have to concentrate on breathing while holding the breath,
these longer Mantra can be recited correctly.”
– TKV Desikachar Religiousness in Yoga Chapter Nine Page 128-129