Young, M. M. (2013). University-level group piano instruction and professional musicians. Music Education Research, 15(1), 59-73. doi:10.1080/14613808.2012.737773
I mostly care about the literature overview here:
Group piano courses originated in Europe during the early nineteenth century (Richards 1962). /…/ By the twentieth century, group piano courses were included in private schools and public elementary schools and in the 1930s were introduced to universities. /…/ Currently, group piano classes can be found in private studios, public schools and institutions of higher education (Tsai 2007). Teachers continue to employ the group piano format because it is efficient and musical skills develop more quickly in a group setting (Kokotsaki and Hallam 2007; Shockley 1982).
Of the settings in which group piano classes can take place, university-level group piano courses are most common (Tsai 2007). University-level group piano courses fall into two major categories: courses for music majors and for non-music majors. Courses for non-music majors introduce non-musicians to reading notation and beginning piano pieces, whereas piano classes for music majors are responsible for developing the functional piano skills that undergraduate music students will use in the future (Chin 2002; National Association of Schools of Music [NASM] 2009; Tsai 2007). Now ubiquitous in universities and colleges in the USA, group piano courses for music majors are charged with developing the functional piano skills that undergraduate music students will use in their intended careers (Chin 2002; NASM 2009).