Offset is used to start from a certain stock transaction. At 0, it will always scan from scretch.
We scan from product 0 to your last product and start again at product 0. This is an infinity loop that continues to run continuously.
Scanning is done every 5 min, with a maximum of 10 products in each scan. So if you have 1000 products it will take about 8 hours for all your products to be updated with the relevant stock.