I've been making my own Christmas cards for about 7 years. The first few years I made them all the same layout, but changed up the paper color and glitter color. Now I make them all different. I usually make about 60 and I might make 4 the same but that is about it. However, several years I've also made sets of 20 to donate to the Juvenile Diabetes fundraiser that my husband's company does. These are all the same.
Even when I bought Christmas cards I would buy different boxes of cards (I was sending about 80 back then) to have a mix. I learned early on to note who got what each year so that if I had some left over, I could use them the next year and not send repeats. Now I use iPhoto to keep track of who gets what.
I also make cards for other holidays: Easter, 4th of July, St. Patrick's Day, Halloween, Fall, Thanksgiving, etc. so keeping track of who gets what is important, especially since not everyone gets a card for every holiday. I usually run out of time and can't make enough for everyone every time.
Sometimes I will make a card with a person in mind (religious ones at Easter and Christmas), funny Halloween ones instead of spooky ones for folks with little kids, Easter bunnies for the lady who has a bunny, etc. but mostly I just pick up a card and put it in the addressed envelope.
So I've done a bit of everything, but mostly I like making different cards.