I sure don't think I have all the answers, and certainly not for other types of LD's. But I do think that I've learned one BIG lesson, and that is that I'm not helping him if we get in an adversarial position over homework. I have to be on his team emotionally. That means helping when he wants my help, but not pushing him or badgering him. I've seen that at least with him, if homework expectations are reasonable, he doesn't need pushing. If he starts to argue and procrastinate, it's a sign that he's getting overwhelmed.
He does need guidance and reminders on long-term projects, and his teachers and I work together on that, setting mini-due dates, and writing chunks into his agenda to be completed week by week. He is definitely not ready to be able to plan and carry out long term assignments unsupported at this time.
I have to say, though, that my younger,non-LD, (at least as far as we know;-) son is 3rd grade too. He has VERY little homework. He is supposed to read with an adult 20 minutes daily, and the teacher doesn't care how this is split up. It can be the child reading or taking turns with and adult, or an adult reading to the child. She may suggest a little push for a child that she thinks is capable of independent reading and is insisting on being read to, but she (and this reflects our school's philosophy) believes that it is exposure to literature that will develop a love of reading. Obviously, if a child is having a problem learning to read, they are put into an appropriate specialized reading program in school, but the time spent on reading at home, for the NT child is meant to foster a love of reading, not to teach reading. As such it is supposed to be non-stressful.
Besides reading, he typically has to write something short (a "hamburger paragraph" often based on what he's read during the week) one night, and do a FEW math problems (a couple of word problems, or about 5 math fact problems) another night. She assigns all homework on Monday, and it is due on Friday, so that families can work around their schedules. Timothy often finishes two "days worth" of homework on Monday, and finishes up the rest the next day, in only a few minutes, and completely independently. She has the same policy that if they have a problem with something, write a note and send it back, but I don't think I've ever had to do it with him.
It sounds like even if your son's teacher is wonderful in other ways, she may be one of those heavier-than-average homework teachers. The fact that she NEEDS to spend so much time with him one-on-one means that he probably needs it. That's what special education is for. If he's still not getting it during the school day, I'd really, really want it documented how much time you are spending reteaching at home. What happens when he's in high school studying Trig? or Physics? Can you reteach that? I sure can't! I want it to be very clear what kind of support my son needs BEFORE that point.