Well according to this: https://spongebob.fandom.com/f/p/3100000000000003418 you should only add the template once all the images are categorised but I'll take your word for it and I won't remove the template from those subgalleries with uncategorised images until I'm 100% sure that the template should only be added once all the images in that subgallery are categorised.
Hey there, you are correct to an extent that all images should be categorised before deleting the subgalleries. The only cases where that is not the case is if the images do not appear in the main episode gallery. Hope this helps! :)
honestly why are you starting to put all subgalleries under candidates for deletion AGAIN when Spongebob456 clearly said that they should only be put under deletion if all the images of that subgallery which are in the main episode gallery are FULLY categorised