Windows 10 scheduled tasks

Hey, so i recently started using the task scheduler to have my pc shutdown a few hours after i leave it, but its becoming a bit cumbersome to manually delete the tasks everytime they stack up, as well as making new ones everytime. So im asking for advice, is there a way to make an ongoing task for this purpose? I know that theres an option to make a trigger for it to do so, but im not exactly savvy so i need your help.
on another note, i got the method for doing so from a random guide, and it involved using the argument "-s". is this a necessity? what does it do?
Just schedule it to run every 30 minute or hour and under the Conditions tab check the box for "Start the task only if the computer is idle for" enter the number of hours when you want it to shutdown minus the trigger time and set the "wait for idle for" to a low value such as 5 minutes
there arent any options that exceed 1 hour. except for the "wait for idle" option that goes up to 2 hours. this is under conditions. Could you perhaps give me a step by step approach? Im not entirely certain what wait for idle means. if i were to set it to the max one hour to run the task, while having it wait for idle set to 2 hours, what would happen? would it mean that the task would wait an extra two hours before coming into effect? or is it just something to tell how long till the pc is considered idle? speaking of, is the pc being idle something that would happen only when its in sleep mode? or is it the moment i stop interacting with it? I hope you can clear this up for me, thanks.