I've got four types of task lists in my system.
There are reactive tasks. This is when a piece of work comes in, there are several stages that it needs to go through as part of our Modular Delivery process. These tasks are only triggered when the work arrives on our desks.
Then there are three other types of task - put simply, there are weekly tasks, monthly tasks and quarterly tasks. These are general housekeeping chores that need to be done at regular intervals. Different people have different tasks, but those levels of repetition work really well - three rhythms within the company - weekly, monthly and quarterly - to ensure that everything gets done.