I have talked to many teachers and homework experts about this. The first rule is that she start the homework as soon as possible. Come in the door. Get a drink and snack, then start. No TV or other distractions until it is done. That provides a useful motivation, and eliminates the pressure of homework conflicting with bedtime.
It is best to start with the complicated assignments, when she is fresh and focused, and leave the lesser assignments for last. Both she and you will learn shortcuts as you proceed. Your daughter will feel better about what she has left to do if the hardest stuff is done.
If you follow those rules and still feel the work is more than she can handle in a reasonable time, call or email the teacher or teachers and seek their advice. Tell them what kinds of homework are most time consuming. In interviewing parents about their homework experiences, I have encountered several stories of kids who were doing too much because they misunderstood the assignment and were too shy to ask questions about it. Teachers will tell you that homework has little or no impact on final grades, and that is true. I will tell you that in 6th grade we have plenty of data that homework has almost no effect on achievement, although by 7th grade it is beginning to have some importance and in high school it does effect learning. For the time being relax, stay in touch with the teacher, and don't let it get to you.