I've moved around a bit on this subject as a result of changing school systems twice in the last year. In the UK both dh and I worked full time. Homework was a hassle, we got it done, but reluctantly and often at the last minute. The children had spellings, reading, a maths sheet once a week, and ds had projects (nightmare). We'd get the worksheets done, and struggle through the projects, but spelling was always a big fight (ds is dyslexic and hated them), and we didn't do the reading with ds because he hated it. HW did not seem worthwhile, and we were not very supportive.
Then we moved to the States, to a school which regularly set up to two hours homework every night. It always had to be returned the next day, and all the local children had it. To start with it was a real struggle, especially as the work covered things differently than we were used to. However it was in fact very useful. The children got into a routine, we understood where they were struggling and needed support, and they got into the habit of reading every day (they had to do book logs with reviews). But it was a lot, and if we had both been working I'm not sure how it would have been done.
Now we are in Canada and homework is reading, spelling and finishing work that wasn't done in class. In a crazy way we miss the US stuff, as it was good to know where they are at, and the discipline was useful. However it is much more relaxed, which is also nice.
In our experience a little bit every night, always due back the next day works the best, and as parents we have a responsibility to support our children. Ultimately if they fail at school it is not their teacher that will suffer, it is the children.