I run a weekly Top 40 countdown show. It’s not one of the syndicated programs, we do it ourselves here. What’s the best way to schedule songs for that?

The goal here is to schedule the songs for the countdown without moving them out of their regular weekly rotation categories (Heavy, Medium, Light or A-B-C or whatever you’ve named them).  You do it with a “Selection” category.
1) Open Categories and select File>New Category>Selection.  Name the new Category “Countdown”
2) When the Countdown Category/Tracks window appears, select View>Copy Tracks.  Search your Current hits categories.  Select all the 40 songs that will be in your Countdown, then click the “Copy” button.
3) Using the Up/Down arrows on the right of the song list, move your 40 songs into proper Countdown order.  Song #40 should be at the top of the list, song #39 will be rank position 2, song #38 will be rank 3 and so on.
4) Click the Parameters tab and put a check in the box labeled “Schedule this category in perfect rank order.”  Also remove any numbers you may see in the Title Separation and Previous Day Separation boxes.  And remove the check mark from the ‘Enforce Artist Separation’ box.
5) Now create a Countdown Format clock and add your Countdown category to it as many times as needed to fill the hour.  Drop this clock onto your Dayformat in the proper hours and you’re all set.
6) Each week, you’ll need to do some updating of the Countdown category.  Open it and remove any songs that are no longer in the Top 40 by selecting the song and doing a File>Delete command.  Next Search your Currents categories and copy any New titles into the Countdown category and re-arrange the titles into the proper countdown order.
If you have recorded Countdown Stagers that you play before each song (“Heeerrre’s Song #38….And Now, Song #25”…etc.) you can create a non-music category for those and format the Countdown Stagers between the songs.
Music 1 LE does not have the Selection Category function.  To schedule a countdown with it, you’ll need to create a clock that is empty of Song categories, put it onto the dayformat, then when you load the new schedule, click to the countdown hours and manually search-and-select the songs for the countdown individually.