I am always surprised by the fact that people (both teacher as parents) focus so much on homework, especially in the US. Not saying that those who have children who do get homework should not care, but I have had more than one (American) parent asking for homework over the last years. Working as a year 3 teacher (7-8 year olds), I never give homework for the next day. I do sign all children up for an online program that helps them improve their spelling, with the advice of practicing this 4/5 times a week for about 15 minutes (can be done on computer or tablet) and I do tell parents to read to and with their children every day if possible, but non of it is required to succeed. Reading does also mean reading recipes, news articles, subtitles or even traffic signs. I do ask parents to practice the Times Tables, but they are free in how they do it; singing songs, practicing in the car of even using fun apps. By the end of the year, we sometimes start giving out workbooks as homework, but even this means a single page of math problems for which they have a full week. And the whole point of that is to teach children to take care of their work when they bring it home and to bring things back in on time. Only when children are in year 5/6 homework is handed out twice a week, but even then never more than 2 pages (30 - 60 minutes of work). School is from 8:30 - 15:00 and on Wednesdays till 13:00, but children here do not score any lower than those in the US or UK.
If you have a child struggling, it might make sense to see if, together with the child's teacher, you can find the goals for the homework assignments. Cause if it is to learn the spellingwords or times tables, you might have different ways to practice, without the whole stress of finishing assignments in time! Feel free to ask for websites ect. if you want to, I might know some that could help and working on a tablet while in the car is much easier than filling in answers with a pencil.