Have you read the post with follow up Spectrolino diagrams after that one? Where calibrations were performed?
which post ? I am referring to the graphs in the following post http://forum.luminous-landscape.com/index.php?topic=108238.msg892565#msg892565
With Spectrolino automated measurements it does force recalibrations fairly frequently - possibly to account for the drift.
with spectroscan table you most probably keep the lamp heated good enough by measuring printed target patch by patch in a quick succession - you can't do the same manually with SG...
whether standard calibration helps or not like the heating request - I think we can do the test... say execute calibration every 10th (or may be even every other) measurement... I need to dig out my Spectrolino... what is clear though that you can't calibrate once before measuring the whole big target
PS: what is also interesting to test is to see how different is drift say between repeated measurements of dark patch (allegedly the lamp is on for a longer duration) and bright patch (allegedly the lamp is on for a shorter duration)