These ensembles, are an important aspect of social life in courts and the larger municipalities. "No prince and no wealthy town could successfully display their significance wihout the services of the wind band." ( K&F pg. 146) In their civic roles, the alta would play in: public and civic ceremonies, weddings, banquests, trionfoni (triumphal entries), in the battlefield, and even at church (although generally it is assumed in a non-liturgical context). This laundry list of venues can also be applied to many of the later ensembles, and highlights the ubiquity and necessity of this versatile ensemble. Please also note that this was rarely (if ever!) dinner music--this ensemble particularly earns its reputation as being loud!
This unmixed shawm ensemble lasted until circa 1450, when it was replaced by the shawm and trombone ensemble. It is unclear how long before 1450 this ensemble existed, but that's okay, as that goes before the limits of my research!