Dust-off reference images are only useful if the dust pattern on the sensor was the same when the affected photos were taken. If the dust changed over those 6–8 weeks, the reference won’t reliably fix older images and could remove spots where none exist.

For practical cleanup, the best approach is usually batch retouching in your editor:

• In Lightroom, use Spot Removal on one image, then sync/copy only the spot-removal settings to similar photos.
• Check each image afterward, because spots may need small adjustments depending on framing and content.
• In Photoshop, images with smooth backgrounds (like sky) may respond well to Dust & Scratches, but detailed scenes usually need manual spot removal.
• If using Lightroom, features like spot visualization can make dust easier to find.

So: yes, you can speed this up for large sets, but fully automatic repair is only dependable when the dust pattern is consistent.