in that order one at a time as daily time allows, is attributed to consultant Ivy Lee (1877–1934) as the most profitable advice received by Charles M. Schwab (1862–1939), president of the Bethlehem Steel Corporation. An early advocate of "ABC" prioritization was Alan Lakein, in 1973. In his system "A" items were the most important ("A-1" the most important within that group), "B" next most important, "C" least important. A particular method of applying the ABC method assigns "A" to tasks to be done within a day, "B" a week, and "C" a month. To prioritize a daily task list, one either records the tasks in the order of highest priority, or assigns them a number after they are listed ("1" for highest priority, "2" for second highest priority, etc.) which indicates in which order to execute the tasks. The latter method is generally faster, allowing the tasks to be recorded more quickly. Another way of prioritizing compulsory tasks (group A) is to put the most unpleasant one first. When it's done, the rest of the list feels easier. Groups B and C can benefit from the same idea, but instead of doing the first task (which is the most unpleasant) right away, it gives motivation to do other tasks from the list to avoid the first one. A completely different approach which argues against prioritizing altogether was put forward by British author Mark Forster in his book "Do It Tomorrow and Other Secrets of Time Management". This is based on the idea of operating "closed" to-do lists, instead of the traditional "open" to-do list. He argues that the traditional never-ending to-do lists virtually guarantees that some of your work will be left undone. This approach advocates getting all your work done, every day, and if you are unable to achieve it, that helps you diagnose where you are going wrong and what needs to change. Various writers have stressed potential difficulties with to-do lists such as the following. Management of the list can take over from implementing it. This could be caused by procrastination by prolonging the planning activity. This is akin to analysis paralysis. As with any activity, there's a point of diminishing returns. To remain flexible, a task system must allow for disaster. A company must be ready for a disaster. Even if it is a small disaster, if no one made time for this situation, it