They have been busted over a period of nearly two years. Sometimes I got helicopter vists (not all of them). I recall the one in the centre of The Hague and also Arnhem seemed to struck a nerve or two, haha. But overall: sylphs, often.
I used HHG’s at first, two or so with a couple of TB’s just to be sure. nowadays, I just make a lot of TB’s and keep tossing till I get the message/feel it’s enough. At least 7-8 TB’s for one of these, and I surround the target. 6 sometimes is enough, but I overgift. Keep in mind that there is almost always water close by here in Holland, which is very powerfull. But I often combine water gifting with burrying. It has worked quite well judging from the pictures. There is only one tower that could have done with some more TB’s. It’s near my parents’ place, so I will get there sooner or later. (the one with only the top antenna showing).
There is another impressive one that soon will enjoy my visit. Perhaps I’ll post it later.