The OLM is uncannily accurate. If you're a suburban/rural /highway driver you can take it as gospel. Whatever it says - and the owner's manual usually amplifies that, when the change oil message shows, do it within the next two tanks of gas.
For more insight, please study the entire Cadillac Technical Archive way up ^^^ in the top black bar. It was written by one of the Northstar powertrain engineers and the OLM section was written by the engineer who developed and verified the algorithms.
Using modern oils and unleaded gasolines an engine can go FAR longer between oil/filter changes. I drive my 2002 less than 5,000 miles a year, so I change oil/filter each April or so. It leaks not one drop of oil and gets over 6,500 miles per quart. Oil sample tests from Blackstone Labs come back with essentially no wear traces.
Study your manual on how to reset the OLM at oil change.