slog vs work to rule

slog

verb
  • To work slowly and deliberately at a tedious task. 

  • To strike something with a heavy blow, especially a ball with a bat. 

  • To walk slowly, encountering resistance. 

noun
  • A long, tedious walk, or session of work. 

  • An aggressive shot played with little skill. 

work to rule

verb
  • To work slowly by strictly following all work rules, usually in a work-to-rule job action, as part of unionized labor protest. 

How often have the words slog and work to rule occurred in a corpus of books? (source: Google Ngram Viewer )