Now don't get me wrong, you need to make sure you know the difference between a long Moodle course and death by scrolling which I'm sure the Core Moodle developers took into consideration when they restricted the total amount of topics in a Moodle course to 52.
Here are 4 of reasons why there is nothing wrong with a long Moodle course.
1. The Mouse has a stroller for a reason, (the scrolly thing between the left and right mouse button) don't be afraid to use it. Imagine if Amazon, ebay or Play.com didn't have a long list of items. would you still browse and buy?
2. Long courses are awesome, however you don't want to confuse your learners by having everything in one very long boring list, try breaking up your course with Topics, Headings, Lables, Images and Videos.
3. Show your learners how to use the the topic show/hide button with the drop down list of all the units. This is core to Moodle and should be used by everyone.
4. Don't be afraid of letting your learners scroll, after all they are the Facebook generation they're used it.