hedge one's bets vs stall (for time)

hedge one's bets

verb
  • To place bets with a third party in order to offset potential losses. 

  • To reduce the risk of making a mistake, by keeping one's options open. 

stall (for time)

How often have the words hedge one's bets and stall (for time) occurred in a corpus of books? (source: Google Ngram Viewer )