Only one reason to ever use a OWE fare: it is cheaper than the alternatives. You can make EXP on a single AONE5 with careful routing (but not outrageously so); bit better than those 10 trans-Atlantic off-season fares, and a bit more comfortable in A. But if you don't want/need to travel to the cities that you hit on a OWE, then it isn't the best value for a pure MR. The best way to look at OWE is that you get a dozen sectors for the trip you need to take and an extra 8 for more trips (e.g. 3 "free" round-trips in NA if you have the right routing and city pairs); also don't forget the OWE tickets are fully changable, with free date changes, unlike most discounted fares. This gives tremendous flexibility within the rules (again the value of this varies tremendously by circumstance, for me it is critical and worth paying double to get it).