I cannot answer soon. But, I think optimal weights are not used in a recent paper of natural language understanding:

  
      
      arXiv.org
  
  
    

Improving Multi-Task Deep Neural Networks via Knowledge Distillation for... 55

This paper explores the use of knowledge distillation to improve a Multi-Task
Deep Neural Network (MT-DNN) (Liu et al., 2019) for learning text
representations across multiple natural language understanding tasks. Although
ensemble learning can...


  
  
    
    
  
  


Please see Algorithm 1 in this paper.