I had a lot of fun practicing this but after some 20k games of chess I've only seen it once, and I was on the defending side. I almost had it once on the attacking side but my opponent resigned if I remember right. It's still fun to learn, and the patterns can help you (for instance, to see how the Bishop and Knight can complement each other well).
Rare end game encountered
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Apparently the king must be chased from one corner to another, if the defense is perfect. I'll just be content having seen it. Once in 20,000? Whoa.
ChessExplained got it in two games very close together in his live blitz games on his YouTube channel. You never know when it might come up. The amount of time it takes to practice the mating pattern versus the amount of times you'll have to use it probably doesn't make it worth it, but again I just thought it was fun to learn and does seem to have some other value in terms of practicing piece coordination. 
I just got through playing an over the board game with a friend. A wild middle game ensued, and after the dust settled, it was my bishop and knight against their lone king. I didn't feel like figuring it out so we agreed to a draw. Apparently this end game occurs only once in every 6,000 games, a "once in a lifetime" thing.