There are a number of reasons for this, but one that I’d never considered until recently is that psychologically it’s always easier to commit to a task if you know how long it will take. I’m much more likely to attend a working bee, join a committee or even go shopping with my wife, if I know in advance what my involvement will cost in time.
Think now, about a student contemplating her homework. If it’s a reading and writing task, she doesn’t really know how long that will take to complete. It could take 20 minutes but it might take 45. Her time commitment is indeterminate. So if she has half an hour ’til bed time, does she make a start on the homework? I offer that many students will put it off until tomorrow.
On the other hand, consider a student with a podcast to listen to. He knows precisely how long it will take, because it says so, right there in the progress bar! He knows he can listen to that podcast in 25 minutes and 45 seconds – leaving precisely 4 minutes and 15 seconds to brush his teeth and put on his pyjamas, before bed. Homework done. Check!