A NOTAM is what it says; the wording is important. Just because it's a "NOtice To AirMen" does not necessarily mean "everyone else is legally banned from entering this airspace, so keep out". Unfortunately, some seem to think otherwise.
Having said that, entering a NOTAM'd area without due consideration is not a good idea.
OTOH, I know of two "semi-permanent" NOTAMs that involved the flying of kites, allegedly up to 2,000 ft agl. One was in a commonly used helicopter transit route/choke point north of the LHR CTR. I looked for months for those damned kites, never saw a thing. Then one day I noticed that the wording had changed and now included a contact telephone number, so I rang it. A woman answered and she knew nothing about what a NOTAM was. I explained in words of one syllable and she explained that her "other half" sometimes flew a kite from a playing field. He only flew it very occasionally for fun and hadn't done so for many months. He was at work every day in the week. Total waste of effort of all concerned. I rang the controlling authority at Gatwick, only to be told that if someone requests a NOTAM, they were required to publish it, whatever the circumstances. Thankfully, that one has long gone.
Another one: a kite NOTAM appeared, for every day, SR-SS. This caused a potential issue whenever I needed to land at an adjacent field landing site, which was of key importance to the business I flew for (it was a large diameter circle, miles wide). I rang the contact number to be told that he was a falconer and sometimes he drove to that area where he trained birds of prey to fly from a perch under a tethered kite, from different locations within the circle. This chap was under the impression that by applying for a NOTAM no aircraft could ever enter "his" airspace, although he wasn't there very often. I explained that I sometimes needed to land very close by "his" circle, he said I wasn't allowed to. I then told him he had more airspace than a major airport nearby, which at that time only had a 2.5 mile radius ATZ. He didn't seem to see that as a problem. I see that NOTAM is still there, but thankfully now based on a much smaller circle.