Our entire homeschooling experience has been fully enrolled with Seton Home Study School. They send all the books and lesson plans for each child along with tests, quizzes, and progress report forms to send and receive report cards. We have found through the years which subjects need more work than the they suggest and which ones need much more. Will is in 6th grade and we have found that the Seton tests for this grade are very difficult to pass without sufficient studying. Today we finished up the 2nd quarter religion test which Seton gives 4 days of study and 1 day to take the 4 page test. Instead, we took 3 weeks to review and test in smaller chunks. It wasn't the Bible history part that was so hard, but memorizing 15 catechism questions perfectly.
I guess we are "technically" behind now, but I use review and tests in religion, history, and science to continue to learn the material, not to trip them up. Unlike mathematics and phonics, which review the same concepts over and over, these other subjects are new material that doesn't really "stick" unless it is covered more than the one reading of the chapter. Yes, we do supplement with Story of the World and non-fiction books, but if we spend a month or more on the material than the lesson plans officially call for and spend more time in review then the children will be better off in the long run, even if their summer vacation is a tad bit shorter.