I think it is harder parenting skill to back off and watch them struggle or make mistakes on their own. Stop looking at it as 'slacking'... I know in my case that it would be twice as hard on me to stand back.
At our house, homework is always a struggle and a fight. DD's medication is well worn off and her attention is non-existant. She detests math and is very vocal about it through every exercise she does. She needs constant encouragement/threats/prompts to stay on task. I have to push her to add details to her writing assignments and to always try her best. She says that she is happy with messy, half-finished work but when she gets a poor mark then she is upset and guilt-ridden. We are trying to find the happy medium between being entwined in the homework fight and standing back and letting her flounder on her own.