When you have the extra time to allow your spaghetti meat sauce to simmer you should absolutely go for it! Simmering on a low heat will allow the flavors in your sauce to further develop and marry together. The longer the sauce simmers the yummier it gets! In fact, this is a great dish to prepare ahead of time and freeze. Then when you are ready to enjoy it add it while frozen into a slow cooker and allow it to simmer on low heat for a delicious and easy week night dinner.