hold on vs sit tight

hold on

verb
  • Wait a short while. 

  • To remain loyal. 

  • To grasp or grip firmly. 

  • To persist. 

  • To keep; to store something for someone. 

sit tight

verb
  • To wait patiently; to take no action; to remain quiet or relatively motionless. 

How often have the words hold on and sit tight occurred in a corpus of books? (source: Google Ngram Viewer )