This is an example of a sample task that reschedules itself, thus creating a recurring task. This is initially kicked off in the Global.asax/Bootstrap section calling MyScheduledTask.ScheduleTask(true).

MyScheduledTask.cs

public class MyScheduledTask : ScheduledTask
{

    public static readonly string MyKey = "<hard coded guid string>";

    public MyScheduledTask()
    {
        Key = MyKey;
    }

    public override void ExecuteTask()
    {
        try
        {
            // Do the actual task work
        }
        catch (Exception ex)
        {
            Log.Write(ex, ConfigurationPolicy.ErrorLog);
        }
        finally
        {
            ScheduleTask();
        }
    }

    // The runNow argument should really only be used for local testing/debugging
    public static void ScheduleTask(bool clearExisting = false, bool runNow = false)
    {
        try
        {
            SchedulingManager manager = new SchedulingManager();

            if (clearExisting)
            {
                var taskName = typeof(MyScheduledTask).FullName;
                var allTasks = manager.GetTaskData().Where(x => x.TaskName == taskName).ToList();
                if (allTasks.Any())
                {
                    foreach (var task in allTasks)
                    {
                        task.IsRunning = false;
                        manager.DeleteTaskData(task);
                    }
                    manager.SaveChanges();
                    Log.Write("Deleted old tasks for MyScheduledTask", ConfigurationPolicy.Trace);
                }
            }

            Log.Write("Creating New MyScheduledTask", ConfigurationPolicy.Trace);
            CreateTask(manager, runNow);
        }
        catch (Exception ex)
        {
            Log.Write(ex, ConfigurationPolicy.ErrorLog);
        }
    }

    private static void CreateTask(SchedulingManager manager, bool runNow = false)
    {
        // GetExecuteTime() is up to your implementation, but make sure result is in UTC
        DateTime executeTime = runNow ? DateTime.UtcNow.AddSeconds(10) : GetExecuteTime();

        Log.Write($"Creating a new task to run next at UTC {executeTime}", ConfigurationPolicy.Trace);

        MyScheduledTask newTask = new MyScheduledTask()
        {
            ExecuteTime = executeTime,
            Description = $"My Scheduled Task, scheduled to run at: UTC {executeTime.ToString("o")}"
        };

        manager.AddTask(newTask);
        manager.SaveChanges();
    }
}