Sometimes it is obvious that help is expected (rubric for first grade only gives full credit if everything is spelled correctly), sometimes I ask. Most of the time, if we help, she put the names on the project as [child name] and we write, with help from [adult name] next to it. We started doing that in K because she did a very cool project with no help from us and had a model due at the same time that she couldn't have physically done by herself. While I no longer believe she is 2E, she is very out of sync and doesn't always feel good about herself at school. It somehow made us feel better in some small way to differentiate between the two so she could be more proud of the work she did by herself. She needed that.
We kept it up as she moved forward. I don't think anyone at school has noticed, but I think it really does allow her to feel more accomplishment with the work she truly does.
I don't know that this would made sense in 3rd-4th grade, but I do imagine we could very well still be drawing guidelines on posterboard for her to write on pretty late in the game, and I wouldn't feel badly about that--or about helping tape and glue if that is not the point and it gets frustrating and I know she's really tried.
If rubrics demand no spelling or punctuation errors, I also imagine that I will demand to proofread, whether she wants it or not throughout elementary school, though I do believe it is better to say "you have x spelling mistakes" than it is to actually find the mistakes for the child.
Some parents may do the kids' homework, but I just don't get the point. How can they ever feel good about what they've done if they didn't actually do it?
I will say, if the school requested that we didn't help with homework, I'd be communicating with the teacher about every little thing I helped with to make sure it was okay.