Yes, time management really can make you not know whether to laugh or cry!
Here's another one (from long ago):
A colleague of mine, whose room was about a minute away from mine, rang me one day and asked me for a phone appointment the following day to discuss something. I asked him how much time we would need, and he answered 15 minutes. I suggested that if it is no more than 15 minutes we might as well get it out of the way immediately. Guess what his answer was?
He explained that he had been to a time management course where he had learned the importance of sticking to what you had set out in your schedule that you will do. This particular hour was already reserved for booking appointments only, so he was unable to discuss other matters - so we spent 15 minutes finding a time slot another day instead
For example, I learned that you can predict how long your tasks will take by using a complex formula which is derived by adding the shortest amount of time task will take, plus the longest possible amount of time, plus six times the amount of time it usually takes, and divide the sum by six. (I am not making this up.)
Not to quibble, but the weighting is actually 1-4-1, and it's a decent back-of-the-envelope estimator for how long a project will take. I never heard of applying it to individual tasks- that's pretty silly.
The key question is if the trainer teaching this is applying it himself for his daily planning and dealing with all kinds of projects and interruptions. Probably not, I would say. On the other hand, I think it is safe to say that most people that give training in GTD are GTD-users themselves...
I encountered GTD in 2007. Despite my struggles with it it's been far more effective than the time management paradigm ever was. I didn't realize how much distance I'd put between myself and that kind of thinking until taking this CBT.
Replace 2007 by 2010 and this sentence would apply to me. I think this is the good news for both you and me about this subject!
I didn't bother to write it down or commit it to memory because it's not something that applies to my situation. There is no "average" length of time to close a sales deal -- it can take weeks, months, or even years in my business. Individuals and organizations can be unpredictable. So you roll with the punches.
Still, it would have been better if I had double-checked the formula before posting it. Again -- accuracy matters.
Research is the same as sales: a project that seems quick and easy may take much longer than anticipated. However, the formula is decent for things like construction projects, where the distribution of completion times has a wing shape: there's zero probability of being really early, but there's a long tail where the project is really late. Thus the formula puts the mean completion time (average) somewhat beyond the mode (the most likely completion time). I don't use the formula routinely myself, because this kind of reasoning becomes intuitive with time and experience. I still can't believe anyone would use it as a basis for scheduling tasks.