I'm afraid that in the current dismal economic climate, the frequency of sales has been increasing so much that past history is not much guide.

If you want to travel in Club departing in May or June, I really would advise booking in the current sale if at all possible. For dates much later than that, I expect there will be another sale which covers them. I'm planning to be in the U.S. for Labor Day weekend but I'm not booking now as I don't want to pin down my dates this early. I'd say there's a 90% chance there will be a later sale I can use. If not, I will MFU (WTP to CW). In the extraordinarily unlikely event that I can't do either of these and really have to pay £2000 rtn to JFK, I'll slum it in J/C on some other carrier.

in 2006 and 2007 I think there was a CW Spring Sale (held around February/March, covering flights departing April to June) and a Summer Sale held later covering flights in August and September. But these sales covered fewer routes than the most recent sales; even the routes that were always included (e.g. JFK) had many months of the year that never appeared in a sale; and F was never on sale at all.