There are a number of reasons why the amount of new pages can drop for short periods. The first is that some newspapers simply take more time to digitise than others, either because they take longer for our machines to 'read' or because they require more preparation work.
Scanning a large volume of newspapers direct from paper can also cause a delay. Paper scanning takes more time than scanning from microfilm as significantly more care is needed when handling the materials. There will also be periods in which we need to make changes to the digitisation system. During these times, we may pause the publication of new pages.
The good news is that as well as low-volume days, we also have days when we deliver a lot of new pages. Over time these average each other out.