Some clients schedule about 50% of their tasks, the rest is handled by to-dos. It's mostly because things happen very quickly: they got a call that something needs to be done and there is no one really responsible for scheduling. Also schedule changes dynamically so it's easier for them to use to-dos instead. They usually create couple of to-dos every day.
To-dos can be created through the Toolbox or through the iOS application or the Web Client.
To create a To-do in the Toolbox click on the drop down menu and select New To-do. Type in a >header and a note if necessary. Select the day, the time and set an Alarm. If it is set as Priority, a yellow triangle will appear next to this To-do line to call attention. The To-do can also be linked to a Project, however it can not be viewed inside of the Project - it just refers to the Project.
What is nice about To-dos is that user gets the notification on the phone and can immediately see that new task was created for him. They can see name of the project and deadline for the task.
When a to-do/task is completed they mark it as done and it disappears from the view.
They also create ad-hoc time report, where they specify how much time they've spent on this task and add services if needed.