That's the recommened amount of finish coats for almost all domestic paints, Ken.

The most durable woodwork/trim paint I've ever encountered (that's not from Europe @ $90 per 1/2 gal.) is BM oil-based Satin Impervo. It's 20 years old in some of my clients' homes and still holding up.

Always call the place you live a house. When you're old, everyone else will call it a home.