In German, two-part composite nouns (Schul·lehrer, Schlüsel·loch, Elektronen·mikroskop, Sonnen·wende, etc.) are abundant, but composite nouns consisting of three or more parts are not at all uncommon: Grund·schul·lehrer, Schlüsel·loch·chirurgie, Raster·elektronen·mikroskop, Winter·sonnen·wende·punkt.
In English, the joining of two nouns into one (e.g. school·teacher, key·hole) also happens, but it is not as common as in German (e.g. electron microscope, not electron·microscope), and, as far as I can tell, it is limited exclusively to two-part composites (one never sees composites like elementary·school·teacher).
But, if one considers only the spoken language, then there's a close syntactical similarity between, on the one hand, German composite nouns like Raster·elektronen·mikroskop and Grund·schul·lehrer, and on the other, English "nominal" collocations like scanning electron microscope and elementary school teacher.
Now, assuming this correspondence between German composite nouns and English nominal collocations, one can begin to formulate questions about the relative frequencies of such entities in the respective languages.
One such question that interests me is whether composite nouns of three or more parts (for which I'll use the shorthand 3+-compounds) are more common in German than nominal collocations of three or more words (or 3+-collocations, for short) are in English. I suspect that the answer is yes, and would appreciate pointers to any systematic research on this question.
(I realize that the description above oversimplifies greatly, glossing over many complications that would get in the way of a systematic study. For example, it is not always clear how to count the number of parts in a composite word. Is it Umwelt·schutz or Um·welt·schutz? Is it Infrarot·strahlung or Infra·rot·strahlung? There's also the question of whether the frequencies of German 3+-compounds and English 3+-collocations should be normalized, respectively, by the frequencies of German 2-compounds and their counterparts in English (i.e. both 2-compounds and 2-collocations taken together). Dealing with such complications, however, is part of what this sort of research typically entails.)