I looked everywhere for the 5.3 Preview successive batch import and found nothing.
My guess is that Epic hasn’t implemented it yet.
In regular 5.1/5.2/5.3 World Partition, there is no need to use tiles as they are simply stitched back into a single heightmap again on import.
Plus most valid World Partition heightmap sizes are prime numbers and can’t be split into tiles.
World Partition also doesn’t use 4033 tiles. That will result in a padded stretched edge.
Valid World Partition sizes are (511 x N) - (N - 1) where N is the number of components.
5.1/5.2/5.3 World Partition has a maximum fixed heightmap size of 16384x16384.
You can’t get over that limit by simply using tiles.
The supposed 5.3 successive batch import is supposed to fix the 16k limit.
If you are instead looking at using World Composition, then I have successfully imported heightmap tile sets up to 250k x 250k with no issues other than a long wait.
But I am using an Intel workstation with 512GB of memory and an RTX-3090.