No trains ever leave my layout. For now, trains are parked in one of two hidden yards, with a total capacity of 32 trains. When more scenery is done, trains will also be parked in surface yards.
Here are some pictures of the "big" hidden yard. There are five tracks. Each track is 120' long, and holds up to 5 trains. Doing the math, that's 25 train capacity.
This is one of the first digital photos ever taken of the layout, and is the best overview of the big hidden yard, circa 2003.
This is a shot taken this week from almost the same spot.
Another early picture.
This one is from 2012.
This is the small hidden yard, capacity 7 trains.
Then there are the surface yards, where trains are built up and broken apart. Capacity unknown at this time.
The scary part is, I may have too many cars still packed away.