SC - A question about adding eggs

[Patrick Hood]

    I hope I'm not asking something that's been asked before, but why is the
egg added as the last, or near last step in each recipe.  I assume it is to
thicken the sauce.  Is this traditionally more like pouring egg into
avaglamadro greek soup or is it dropped like egg drop soup or is it assumed
to already be cooked and crumbled like some spainish recipies?

I have had great fun reading through these recipies.  And ask because I have
become a periodiphile now that your work has made it seem less daunting.

Nykademus