I just tried to import a lot of photos (about 450 gig taken over 15 years) into a new catalog on a new hard drive. I am using Lightroom Classic 9.3 on a 2013 Macbook Pro running OS 10.15.5. Photos were moved into folders correctly based on Capture Date in the metadata. However, photos that actually show up in the catalog is another story. Many photos don't show up in the catalog at all. For example, there are about 200 photos in the 2000 folder, none of which show up in the catalog. There is a 2000 folder in the catalog but it contains zero photos. Other photos show up in the catalog but they are all showing up under the wrong dates. The dates aren't even close to being right. When the import completed, I got the error message about files not being imported but there were all of three files that it said did not get imported. Did I do something wrong during import? Is there a way I can get the catalog to match the data in the folders/subfolders?
450 GB of images in a single import seems to be a bit ambitious for Lightroom in my opinion. I think it would've been better to import in smaller chunks and take a little time to ensure that the images were being placed where you want them. Since you are adding needs to a new catalog, it might be well to arrange them the way you want them and then import them using the Add option rather than moving them again. But now that Lightroom has moved them it's going to be difficult to know where the images really are. It's also difficult to make suggestions without knowing what your other import options were, such as how you instructed Lightroom to build the folder structure.
Yes it may be better to try smaller batches. You could create a new catalog:
File >> New Catalog
Choose a new catalog name and save by clicking Create
When the empty catalog opens try importing again.
You could start with the 2000 folder, perhaps when moving, choosing a new sub-folder e.g. 2000 New and then selecting dated folders. The destination panel should give you a preview of how many dated folders will be created and the number of files in each.