I watched Big City Blues because it features an early, uncredited performance from Humphrey Bogart. Given the film’s obscurity, my expectations were low.
Until a 1948 Supreme Court ruling, the five major Hollywood studios controlled the entire movie business, from production to distribution. The studios contracted performers and paid them a salary. The performers worked five days a week like anyone else. When one film wrapped, they moved to another. Thus, films like Three on a Match came stock-piled with current and future stars.