When I turn on my Apple Studio Display (15" LCD), and adjust the tracking, I have to adjust the tracking again after about 20 to 30 minutes to get the best results.

The monitor takes approximately 20-30 minutes to reach it's normal operating temperature. For best results, allow the display to reach it's normal operating temperature before adjusting tracking, using the Monitors and Sound Control Panel.

Note: This is for the Apple Studio Display (15" LCD), rev. A or B.