fits and starts
To do something in “fits and starts” is to do it intermittently or sporadically: “Martina has been working on her master's thesis in fits and starts; she needs to work on it consistently.”
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.