This would also be desirable for conditions.
What we find is that as we become more familiar with Visual Cron, there are additional features we want to add to existing jobs. Since our stable of existing jobs is rapidly growing, it is increasingly time-consuming to have to edit each job individually, rather than having a global menu that can be checked or unchecked for each job. (This would be useful for any feature of Visual Cron for which it would make sense.)