I'm curious what factors might cause the job start time to drift? Isn't this a coordination problem? You want all of you employees to start at the same time,

I'm curious what factors might cause the job start time to drift? Isn't this a coordination problem? You want all of you employees to start at the same time, so the assembly line can keep operating. All the kids start school at the same time, so they can all be instructed at the same time.