How should I configure my scheduler to make sure it's runing the last day of every month, whether it's 30/31 days or 28/29 in February.
Will 31 as an N-th day do the job ?
In case of ACC, you need not worry about the value. It automatically calculates the Last day of the month, you will notice this when you click on Next after the step highlighted above.
In case of ACS, I am not sure if keeping a value of 31 would help in case of months having last day as 30/February.
You could try that once and see if it works.