Ashtangasamgraha 28.54

28.54

And three enemas destroy the doṣas successively even in a combined vitiation of all three;
hence, according to Master Caraka, no enema is considered beyond three,
for there is no fourth doṣa against which it would be given again.
Fruit, kṛṣṇa, hemp-leaf, surasā, yaṣṭī, and mārkava.