I have in the past, but rarely... the problem with levy is that it's mostly only interesting in the first 2-3 eras...after that, usually, the CS units are too few or too low level to be of any uses...
Many times in the start games, I don't really have the money to waste on this... there are so many other better options for spending my gold than this... after that, I usually DO have money
to waste on things like this, but... it's has become useless to do so...
I hope that what I consider a BUG that makes it so that CS never really devellop an intersting army in mid-late game gets fixed one day to that this option becomes interesting