It can’t be overstated, a flow chart is but one way to make it through a curriculum. You don’t want to get fouled up like @MaineLonghorn did by making a mistake, but you don’t want to be rigid either. In fact, getting off the path can be useful. My son found a very helpful way to visualize this. He printed a flowchart and then used colored pencils to draw in all the prerequisite paths. One, it helps to not miss a class that would delay progress, but two, it illuminates classes that aren’t tied to any prerequisite background. He took some of those much earlier than the chart indicated and some much later.