As I am sure that you are aware, the time premium is modelled as an exponential function. However, as far as the MNX is concerned, this does not seem to be the case. It is all a matter of how good one can call the tops or botttoms.
For example, I was ahead by one point on my position but did not take it. Now time is rapidly running out and if we do not sell off soon, I will be out my investment.
I have not modeled this yet, but my gut feelis that it is smart to roll these options with three weeks left to expiration if there is any doubt re: profitabilty of a trade.
More to come...