I never said you engaged in ALL of them every month, but who knows maybe you do.. but the list is pretty complete, and any breathing human is pretty much going to be guilty of at least one of them on the outside monthly, probably far more often than that.
Go see for yourself...
http://www.saintaquinas.com/mortal_sin.html
I am hard pressed to believe any conscious living person has not engaged in some level in at least one of these on a fairly regular basis... obviously some of them I doubt most people have ever engaged in... yes, engaged in willfully and with full knowledge of their nature.
We are all human, and we are all flawed and failed creatures... so to think we get through a month without a lesser urges occasionally coming to the fore, is pretty laughable to me.
Now if you want to talk specifically about "lesser urges" which I suspect is another way of referring to masturbation without coming right out and saying it, you might be surprised what a practicing Catholic in the state of grace with the help of God is capable of avoiding. It also helps to be married. ;-)
This is not to say that I have never been guilty of mortal sin...absolutely have....but not on a weekly or monthly basis as you suggest. Catholics that go to confession on a regular basis and receive Christ in Holy Communion while in a state of grace receive additional graces to combat such sins.
If I were Roman catholic I'd never let the priest out of my sight I'd be so scared I'd committed a mortal sin without knowing it.