I give my students two problems a night — challenging, standards-based, assessment-grade cuts off Algebra's prime rib. They can choose from the easier or harder problem. It drives me nuts that some students will still blow off such a low-volume assignment.
I was threatening my Algebra 1 sections with an increased problem count, increased reward for completion, and increased penalties for non-completion as of the second semester, which started today. Then I graphed their first semester grades against homework completion and gave up.
Then you have my three sections of remedial Algebra, which behave more or less as you'd expect.
It's all very troubling.