in fits and starts vs irregular

in fits and starts

prep
  • intermittently, jerkily 

irregular

noun
  • A soldier who is not a member of an official military force and who may not use regular army tactics. 

  • One who does not regularly attend a venue. 

adj
  • without symmetry, regularity, or uniformity 

  • rough 

  • not regular; having sides that are not equal or angles that are not equal 

  • whose faces are not all regular polygons (or are not equally inclined to each other) 

  • nonstandard; not conforming to rules or expectations 

  • not following the regular or expected patterns of inflection in a given language 

How often have the words in fits and starts and irregular occurred in a corpus of books? (source: Google Ngram Viewer )