Having Fun with Physics Homework

I keep surprising myself with how engaging this new career of teaching is becoming for me. I am actually enjoying even grading tests and homework because I want to know how my students are doing. I expect this joy may fade with the years, but it is consoling for now that I am on the right track in finding a fulfilling career in teaching.

On the subject of homework, I am still struggling to find the right balance for students as well as myself. Grading and entering those grades into the computer system is time consuming with only two classes. Five or six classes would be unsustainable even at two or three homeworks per week. But how will students learn physics if they are not practicing the problem solving? So here is a question to throw out into blog world: what is an appropriate homework frequency for high school students? And as a follow up question, what is reasonable for accepting late homework assignments? I so dearly want my students to succeed that I have been accepting assignments weeks past the original due date, but this is a grading logistics issue. I have forgotten the solutions and struggle with the time needed to get back into the grading system for each late submission. At this point I am cutting it off at the end of the unit. Any suggestions out there?