The base cow isn't a made up cow, she's the average national cow (on a particular date) being used as a reference, all EBI figures are then compared to her. Average no. of lactations per cow is 3.3, so that is what is happening on Irish farms. Its improving slowly, but I expect it should speed up now with herds starting to mature with better genetics.
Believe me when I say that ICBF is the envy of the world and is only criticised by Irish farmers. We could be doing so much more if we recorded a lot more information. We could be breeding for lameness, genetic resistance to parasites, mastitis, pneumonia, bull fertility, to name a few. When you talk to people involved in compiling these figures, you'd come away feeling that us farmers are really letting ourselves down and that with the simple act of pulling the phone out of our pocket and putting in a hoof paring event on a cow, we would be adding to a statistic on a genetic line that would give massive information on bull trait selection.