is there a way to have the automation be a different length to the pattern itself?
So a pattern of 64 lines, has maybe just an automation track of say 24 lines repeating?
Or can phrases be used in this way? for storing patterns of just automation?
No.
The closest trick, I think, would be to use the custom envelope of an LFO device instead of the automation lane. It doesn’t have the exact same features as automation lanes, but pretty close.
Make sure to set the Frequency LPC correctly, and to trigger a reset command at a fitting place (like the start of your song, or the start of each pattern). This way, you could theoretically use LFO’s as “automation banks” and switch between them with the usual automation.