No exaggeration here, but I'm slowly learning it's unusual. I've actually never kept an exact count; didn't see much purpose in it. But I'd venture to guess I've hit the 20 mark a time or two.
Granted, my ejaculate becomes more viscous over the period of such a session, beginning with a normal white consistency and ending with a silky silver like pre-ejaculate.
I did the math a few weeks ago and realized that I've ejaculated as many times in my 17 years of sexual activity as most men do in an entire lifetime (roughly 20,000).