We actually used to offer a lateral-only course but found that too many vertical topics included information pertinent to the lateral exam and ended up being part of the lateral course anyway. For example, things like wood connections, steel beam and column design, concrete flexure and shear design, retaining walls, piles, general analysis, methods such as moment distribution, and so on are all topics that have aspects related to both vertical and lateral. Plus, any general exam topics we discuss in the vertical lectures would need to get repeated for the lateral only people.
We only just eliminated the lateral-only course this fall, but have gotten some feedback that some people didn't like this if they already passed vertical, but it was mostly for homework reasons. We're probably going to keep it as is unless we get a lot of feedback that a dedicated lateral only course is highly requested.
The other option would be to have a lateral only course with the understanding that you might be missing out on the basics but I'm not sure PPI would include their passing guarantee with this and it would require rearranging our lectures a bit. Overall it's probably not the best way for us to go with how PPI has set the course up.
Annoyingly it's almost impossible to please everyone with an SE exam review course as some people need vertical only, some people need lateral only, some need bridge focus, etc.