The phrase "unmanageable workload" means having too many tasks or responsibilities to handle efficiently. It implies that the amount of work is overwhelming and difficult to manage effectively. Full definition
Bousted has cautioned that stagnant pay coupled with unmanageable workload is «causing teachers to question whether it is worth remaining in the profession». (educationbusinessuk.net)
While the latest versions have introduced more flexibility for teachers making judgements and increased the focus on composition, they cause confusion and add to an already unmanageable workload. (atl.org.uk)
With 1.3 million children under performing in the UK (Ofsted, 2016) and 74 % of teachers considering leaving the profession due to unmanageable workloads (TES, 2016), it is clear that the current education system is facing some serious challenges. (qaeducation.co.uk)