Three to four times a year, usually.
Sometimes they will be three weekends, sometimes four.
They are always fun, with the right attitude. Sometimes you get the plane you want, sometimes not, but to be immersed in the event to the point of practicing if practices are called, and committing to the full event is always a great experience.
Every once in a while the CIC (Commander in Chief) of the side you are on will not be as good as he or she could be, and your side might take a good beating. That's where the good attitude comes in, knowing that you did what was asked of you to the best of your ability, and did all you could to follow orders to complete your assignment, then coming back the following week to try it again.
We look forward to having you in the next upcoming scenario. Watch this thread, and they (probably an old guy named ROC) will post when signups begin. Sign up early to help get the ride of your choice. They will often ask you for a second and even third choice, in case your first is already full up.
See you in the Pacific Theatre of Operations very soon. (As the joke goes, "two weeks.")