Just one thing do clarify: by "reading" do you mean the psalms being spoken r a bit chanted (a kind of melorecitation)?By reading, I mean chanting in the traditional manner used for the Hours/Six Psalms or Scripture Readings (recitative chanting on one note).
OK, I've asked, because, indeed, here in Polish Orthodox Church we use "reading" for the recitative chanting, but some certains prayers are just really read (i. e. said), e.g. the prayers before the Communion, prayers on the kneeling Vespers on the Pentecost Sunday, some prayers during the minor blessing of the water etc.
Moreover, there are different melodies for the OT Readings, for NT readings and for psalms/prayers, even there are more differentations (e.g six psalms, but unfortunately it's almost forgotten here).
So, here in Poland the kathisma 18th is read (recitative chant), however in slower manner than other psalms - that's what I've been learnt to do, since at least a few times I read this kathisma during the Lenten Liturgies.