As mentioned in mudrd8mz's review of MDL-57831 (copied here for posterity):

PR 1.3 - Usability of this table is not great. Once the user scrolls down and the table columns headings disappear, it is no longer clear what each of the switches actually does:

PR 1.4 - Same problem, but from accessibility perspective. The input elements don't have useful labels. And the same useless text is used for the label as well as for the accesshide title. The label should really give the full information like "Course completed - Web - Online". But ideally, both 1.3 and 1.4 should be redesigned in a way that is both usable and accessible.

PR 1.5 - The headings used at the list do not have right level as reported:

Note the same applies to the message preferences page, which is being updated in MDL-71403