If your scanner can recognise multiple photos and generate a files for each of them then there will be no issue from working more efficiently. You can scan multiple photos in a single scan if you wish. The advantage is that you will save some time in the scanning process.
However, if your scanner will create a single file with multiple images, keep in mind that you will then need to crop each scan multiple times to match the size of the part of your scan that contains the photo you are placing in your book. This takes time, so the times saved in scanning may well be lost by the extra effort required to place each photo in the book.
Additionally, you will not be able to make use of any software functions that highlight used images or can hide used images, as the software will not be able to track whether or not a single scan contains multiple photos. Thus, unless you have scanned items in the exact same order you need them placed in the photo book, you may lose some time keeping track of what photos remain to be placed, and risk leaving some out accidentally or placing some twice.
If at all possible, it is best to have one photo or item per file.