Processing multiple results.fits

I now have around 3,500 images with an integration time of ~29hrs. When trying to process these with OSC_PreProcessing_WithoutDBF I get an out of memory error. So, I tried preprocessing each of the results.fit files from various night’s images and it worked! But my concern is there might be some loss of data along the way with other effects I’m not aware of.

Is processing multiple results.fit a sensible way to go or is there some better way of getting a 29hr+ integrated image?

Nope. This is not a good idea, at least for stacking where it is better to use the whole stack. You should try to understand why you have the memory error and fix that.
Maybe you could try a manual preprocessing too.