Overstaffing means that you don't have your "hukou" at work. To put it bluntly, supernumerary teachers are temporary workers! Not only teachers have supernumerary staff, but also the four public service systems of science, education, culture and health have a large number of supernumerary staff.
Extended data:
Specific differences between compiled and non-compiled
First, the establishment can be mobilized, the corresponding title salary can be promoted, and you can enjoy the corresponding social security and occupational annuity after retirement.
Second, school teachers who are not prepared often belong to temporary employees or labor dispatch teachers and cannot be promoted or transferred, that is, you only belong to temporary employees of a school (commonly known as substitute teachers or after-service teachers) or employees dispatched by labor service companies, often without professional titles or even professional title wages (teachers who are not prepared cannot be employed with professional titles). After retirement, the treatment will be implemented according to the contract signed with the original unit.
Non-staff personnel lack a sense of belonging, security and identity, can't feel at ease in their jobs, and often change jobs, which makes the normal work of the unit passive; Because "supernumerary personnel" are temporary, they often only pay attention to short-term effects and have no long-term plans.
References:
Baidu encyclopedia-supernumerary