@soze Actually, for musical organizations, it can be that complicated.
At my daughter’s university, there were two wind ensembles. The one that traveled and represented the university off campus had the correct instrumentation, and places in this elite group were offered only to those who scored highest at the annual auditions. The other ensemble, which performed only on campus, was open to everyone who could demonstrate that they had enough skill to play the music. If 20 alto sax players could play well enough, then all 20 got in, even though the correct number of alto saxes in a wind ensemble is 4.
But this was a big university. A smaller college would have to choose between having one of these types of wind ensemble or the other.