In the 2015-16 academic year, this service ran regularly. It has been cancelled for 2016-17 and I know a considerable number of students who this has negatively affected (those who are coming/going not just from Yate, but from other areas on its route).
Bus routes to Frenchay are currently overwhelmingly urban; they come to & from the centre of Bristol (which does make sense). The number of services from more rural areas, however, is currently too low to provide an effective service for many students who live locally but not within walking or cycling distance.