I'm new to Affinity, and I'm so far very happy with the 1.7 update (holding shift when drawing! yay!), but the continuous mode has been very slow for me, and I'm unsure what actually triggers it to run. I do a lot of 3D texturing which means making small changes in Affinity, then switching to Affinity or Blender to see how it looks on the model itself. In 1.7 I keep having to click around randomly in affinity trying to get the continuous export to run.
personally, I would be fine with a keyboard shortcut to manually run the export all option in the export persona from anywhere, preferably without the overwrite warning after the first time.