I have a problem with homework that has to be a particular day, but homework that can be completed at a convenient time throughout the week is reasonable.
The problem is extra-curricula activities generally wipe out an entire afternoon. For example, in my household, we have:
Monday night - childrens theatre group (6:45-9pm so children really need some downtime afterschool, not to be plowing through homework)
Tuesday afternoon - private drama classes (we get home at 5:30pm, then it is a very quick dinner, bath and bed)
Thursday night - girls brigade (6pm-8:30pm, arriving home after 9pm. Some downtime is needed after school, and then time having dinner and getting ready.)
Friday afternoon - off to Dad's house.
So that leaves only Monday and Wednesday afternoons available during the week to do homework. I would much rather schedule homework in for Sunday afternoon, but unfortunately the primary school gives it out Monday and requires it back Friday so it cannot be completed over the weekend. Thus it really is a cram to squeeze it into two days.