Brahma Sutras – According to Shankara 3-1-5
Topic 5 - The entire descent of the soul takes only a short time
नातिचिरेण, विशेषात् ॥ २३ ॥
nāticireṇa, viśeṣāt || 23 ||
na—not; aticireṇa—in very long time; viśeṣāt—on account of the special declaration.
23. (The soul’s descent from the moon through the various stages up to the earth takes) not very long time, on account of a special declaration (of the Śrutis with respect to the stages after that as taking time).
The question is raised whether the descending soul, when it attains similarity of nature with ether, air, etc., remains in those stages pretty long, or attains the next stages quickly one after another.
This Sutra says that it passes through them quickly.
“Then he is born as rice and corn, herbs and trees, sesame and beans. From thence the escape is beset with many more difficulties” (Chh. 5. 10. 6).
Thus the stages after coming down on earth through rain the Śruti particularly characterizes as hard to escape from, thereby hinting that the escape from the earlier stages is easy and attained quickly.