The save block (or section; a term more in-line with what Bulbapedia uses, relevance being the image I’m about to share) shuffles with every save. So there isn’t a fixed location.
Source: https://bulbapedia.bulbagarden.net/wiki/Save_data_structure_(Generation_III)
The section ID (what he’s using to identify the save block numbers) can be found at every 0x??FF4 interval (?? are incremental hexadecimal values starting from 0), so if you’re into checking the data via Hex, this is how you can identify the sections.