Well, after having issues with Chynna recently, I learned that throwing up is not "usual" unless it's a hair ball.
Chynna has never had problems with hair balls and they pass with her poops. However as she got older...maybe around 12 or so, she started to throw up daily. Sometimes a few times per day. Sometimes there would be a small hair ball, other times it was undigested food and sometimes just bile, or a small amount of clear frothy liquid.
At the end of February she was diagnosed with high blood pressure. I started giving her 1.24 mg of Norvasc (a blood pressure medication) each day, and her vomitting episodes have amost completely ceased.
The other day I woke up and she had thrown up 2 small amounts of undigested food during the night. Not sure what that was about, but it was more than likely that she was in need of her blood pressure pill.
According to the vet, when a cat vomits it's often a sign of something else. In the case of Chynna throwing up it was due to her high blood pressure.
My 10 year old cat Abby will throw up every day or every other day. But it's hair ball related. She will go and gorge herself on dry food, literally swallowing it whole. Then a few minutes later go and throw up the dry food, followed soon after by another throw up of the remainder of the dry food and a hair ball. But that is the only time she ever vomits. It's her way of expelling hair balls.
I'd suggest taking your kitty to the vet and having him looked at, especially his blood pressure. It's possible that he's throwing up because something else is wrong.