Summary:

A/B test on subtopic pages was performed for a few months.

- Existing subtopic pages with expanding sections ('show or hide' or accordion control)

- Alternative subtopic flat list with subheadings and dividers to organise the content

Half of the people who visited the subtopic pages saw the accordion design, while the other half saw the newer list design.

The data showed quite clearly that the list design performed better, for both desktop and mobile users.