A load, typically a heavy one.
Training a trainee is safe and does not add much burden to the hospital. A trainee will benefit the most if they have the same supervisor at least for the first eight cases and that each case should be done within 40 days of each other 1).
1)
Phang SY, Martin J, Zilani G. Assessing the safety and learning curve of a
neurosurgical trainee in performing a microvascular decompression (MVD). Br J
Neurosurg. 2019 May 21:1-4. doi: 10.1080/02688697.2019.1617401. [Epub ahead of
print] PubMed PMID: 31111746.