I would never do that with a liquidsoap script. The correct solution is to do it directly in airtime and have the power per smartblock/playlist (thus for every show seperatedly) to be able to deside how often you want jingles/spots etc... and i already did this as you can see in "Airtime Hacks" BUT in order to do it there, you need to know what you are doing and its far more difficult than with liquidsoap (you mess with airtime source code) so my opinion is that if you dont even know how to do it yourself then let it be since you are talking about a production server. Create a development airtime copy on another server if you have this possibility and do your experiments after you always keep backup of the files you mess with.