As many American businesses struggle to fill jobs, some have started negotiating demands that used to be non-negotiable for most hourly employees. One of the top demands for many workers is scheduling the days and times they spend on the job. Hourly workers are now seeking more flexibility in their schedules. That means employees are pushing back against requirements to work weekends, late nights or holidays. There are currently many job openings in the United States. So workers can be more careful about the jobs they choose. There were 10.4 million job openings at the end of August and 11.1 million openings the month before. Those numbers are the highest since at least December 2000, when the government started recording the data. At the same time, the U.S. Labor Department said the number of people quitting their jobs jumped to 4.3 million in August from 4 million in July. A recent study from employment company ManpowerGroup found that nearly 40 percent of jobseekers worldwide said schedule flexibility was one of their top three issues in career decisions. SnagAJob.com, an online marketplace for hourly workers, says the word “flexibility” now appears in about 11 percent of the more than 7 million job postings on its site. That number was around 8 percent earlier in the year.