All advice about learning the machine aside, you may have pointed out something odd / counterintuitive about the way parts are used in the demo project, and demo projects that come with some OT sample packs
I don’t remember much about the orig demo on my mki, but I think it was like the demo bank you used to get with the earlier sample packs - the parts allocation could be interpreted as a pretty unlikely scenario in actual use.
They’re not great demos for reverse-engineering and learning the machine as most of the samples are phrases rather than one-shots. What this means is that most of the sequencing is fx / mangling oriented. When you change parts you’re just putting another bunch of phrases through another mangler! it all just ‘works’ because the phrases are quantised and in time, but it’s a sort of wildcard setup - something you may get into with the OT with time, though you’re probably thinking in terms of building songs rn
those demos also switch out the effect types used in different parts, so you might even have scenes or locks acting on irrelevant or non-existent parameters with some parts.
Playing with the demos was also where I noticed that the part changes were happening at differing points per track. (Search here for part change bugs)
Parts are weirdly implemented, a bit buggy, but there’s no real ‘correct’ use of parts. just whatever you come up with.
Merlin’s ‘back to base’ (after going awol with effects) is probably a more common scenario
I use them mostly as parameter snapshots/backups, or to send program changes on the midi side.