Right now, three times, as often as Grenchen (which held two of the previous three, whereas the first two in Apeldoorn are quite a while ago)
Infrastructure is always excellent there, so there isn't really much of a problem with a relatively niche sport going to a well-known quality location more often, I think. Don't want those tournaments where like 15% of the stands are filled, which we'd sometimes see in sports like track cycling.
I also wouldn't mind it being whereever else by the way, as long as the atmosphere is great, I truly couldn't care less exactly which city it is in
Apeldoorn is close enough to often pass by there on my slightly longer cycling trips (one of my main 50+ kilometer laps), but I don't think I'll be going there this year. Funnily enough, Omnisport is right next to one of the parks where clients of my employer live, we were there in December and while walking through the park one sees Omnisport towering over it.