Another grading technique I use for the notebooks is assigning a "catch up" day (usually a Friday and in conjunction with a quiz). As students are finished their quiz they get their notebook and work on completing the required pages. Then they come to me to get their notebook checked. I have a spread sheet and I mark off that we met and what grade they received. I can do a lot of grading quickly that way. I am usually left with a handful that I still have to get after class to grade but it is less cumbersome. This is a great way to get the coloring done, which is the one thing that tends to get pushed to the side if we are running out of time.
If you periodically grade this way it is important to have something for students to do when they are finished. For forth grade that is easy....you can have them make a poster of some topic you have been studying to put up in the classroom, you can let them check out the nonfiction section of your bookshelf and read up on any topic they are interested, you can make word searches or crossword puzzles to work on (if you have taught students how to make them they can go onto the computer and make them on their own). I have even found some science themed coloring sheets online and used that. As long as they are engaged and not bothering other students I am generally happy :)
This is a great way to get stragglers finished with their work.