There are probably a million ways to grade, just as there are a million ways to homeschool.  I only know two.  Neither is wrong or right.  They are different but both acceptable ways of doing it. 

First, there is the traditional.  Teach it, grade the paper, follow your lesson plans, move to the next lesson.  I do use this method with some of the subjects I teach my middle school child.   I do still expect her to go back and correct wrong answers.  I usually use the method below.   

For my elementary children I use this method but it can be used all the way through their education.  Teach (or present), and let the child master it.  This may take some time, and sometimes it takes no time at all.  Some children need to be presented with a new idea three times before it soaks in.  Some times over days with other lessons and "victories" inbetween.  If my child doesn't understand,  I realize they need time with this new idea.  Maybe their brain didn't make a connection on a piece of information they need before this one, or they were tired from staying up to late the night before, or perhaps it is a concept that they are just NOT capeable of understanding yet.  Me pressuring them, or bullying them or loosing my temper is not going to make them get it.  And it wont make me feel better either.  I handle this by not bring it up.  They realize the lesson during their play.  Very often it is the next day or within a week, but sometimes it takes longer.  The child's work of play makes it clear.   

We must remember that children do need down time of play and of rest in their schedules.

For those of us with a "slow" child this is a better way to look at school, although any child can thrive with it.  But to let go of the "I'm a teacher" and hang on to "I present and it is the child's responsibility to learn it when they are ready." lets a lot of stress off.  We must also remember that keeping that child well fed with healthy food, good sleep, happy relations, and hearty activity is just as important to their learning as the lessons we plan for them. 

I can't tell you how many times I've heard the words joyously ringing from a young sweaty child "Hey Mom!  I get it!  I know what you were saying."  More often my children get a concept the first time I present it to them.  They receive an M for mastery.