Who says they aren't? Who says the "Hail Mary" is the only (or even most common) prayer "ordered recited for penance"?
Are your speaking from personal experience? Have you interviewed a statistically significant, randomly selected sample of lay Catholics (or priests) on the topic?
I'm honestly curious ... this is not a flame.
I don't know that they aren't. I'm just asking for Natural's personal experience. I've never been to a Catholic Confession, so I'm admittedly ignorant of the types of penance, but it would appear that Hail Mary's and Our Fathers and recitations of the Rosary seem to be a common thread for those seeking penance. I'm just wondering if any priests have ever suggested that in order to do penance, that the sinner recite chapters from the Book of Leviticus or some other difficult scripture.
Just curious man. Educate me. You guys have been to confession hundreds of times (sometimes I suspect after losing your tempers on these threads) so tell me if I'm wrong from your own personal experience (YOPEWC) "Your Own Personal Experience with Confession"