for keeps vs until the cows come home

for keeps

prep
  • With an agreement or intention to retain what one gains or receives. 

  • Permanently, so that one can keep something indefinitely. 

  • With a strong competitive resolve to win or succeed, as in sports or business. 

until the cows come home

phrase
  • For a very long period of time. 

How often have the words for keeps and until the cows come home occurred in a corpus of books? (source: Google Ngram Viewer )