What curricula/systems are you using that you have to grade so much? Are you grading on a daily basis? That is something I wouldn't want to do... I look over my kids work & if there is an error we go over it together (sometimes I'll give them more practice or examples) but they aren't receiving actual grades on daily work.
My mother homeschooled all eight of my sibs, but she was very low-key about it. (Don't be afraid to do what works for your family, if it doesn't work for you, you won't want to keep it up, even if it is going well for your children!).
Older children (in my experience!) can grade their own work-we used Saxon Math, and each day there were about 25-30 problems to do, a cumulative assortment. After about grade 6, we would grade our own, and go back and correct what was incorrect, up to three problems each day. If we had missed more than three, we went over the lesson together. If not, mom would just glance over our (graded & corrected) work and we were done with that subject for the day, and moved on. That is what I plan on doing when mine advance in grades & maturity (my oldest is in 3rd grade and all our lessons are still very interactive). I think letting a child go over their own work is empowering and leads to child-led learning, and encourages them to seek out understanding as opposed to being more passive receivers of information, which are very important skills for higher learning (as long as you are making sure everything stays on the up & up!).