For our application we are on the same gcode line for extended period of time (Long and slow runs)
You will want to enable segmentation of long moves, which splits them up into shorter moves, and means the move is interruptible. See the general CNC guide for configuration that may be applicable to your setup: https://docs.duet3d.com/en/User_manual/Machine_configuration/Configuration_CNC
There is a limit on the number of steps a move can be, which may be relevant. I think it is 2^32 steps (@dc42 ?). It’s possible to hit this on a long or rotating axis that has a high number of steps per mm.
Ian