There are, of course, many factors that would come into play with regard to this question. The basic rule of thumb should be that the less dangerous a driver's conduct, the less likely the officer should be to cite them. This should take into account how far over the limit the driver was going. It should take into account the time of day and the amount of traffic on the road. It should take into account weather conditions. When all of these factors are considered, the officer should cite people who are speeding in circumstances that are truly dangerous and warn those who are not.
Of course, this should also depend on the driver's history. A driver with many tickets should be given less leeway than one who has a clean record.