A Friedman Unit is not a fixed measure.
It may be so in terms of time, ie; a set 6 months period, but time is the only constant factor and the true value of a Friedman Unit has increased over time, to almost double its original value now.
When first used at the beginning of the Iraq Invasion (by Donald Rumsfeld just prior in February), in the 6 month period between March 2003 to August 2003, a Friedman Unit encompassed 289 killed US service personnel.
Now, in the most recent 6 month period of the conflict, October 2006 to March 2007, a Friedman Unit encompasses 532 US servicemen and women killed.
A whopping 84% increase in 'value' of the Friedman Unit since the beginning of the war. Yet it is used as if its value hasn't changed at all, eg, "...blah, blah in the next months, if...". If the number killed were the constant value, then a Friedman Unit would be valued today at only 3.2 months.
Of course, the value of the Friedman Unit is variable in terms of who you count. Counting wounded, the value of a Friedman Unit is far higher in numeric terms.
Or, counting Iraqi deaths, using the official death toll for the last six days, March 27 to April 1, and extrapolating that out to six months, the Friedman Unit is valued at 15,379 killed men, women and children.
So, whenever you hear anyone using a Friedman Unit and saying "just give it another 6 months", they are actually and literally saying they are prepared to let another 500 US soldiers and 15,000 Iraqis die.