Linked from the article is the final A/B test they ran: https://www.mediawiki.org/wiki/Page_Previews/2017-18_A/B_Tests https://www.mediawiki.org/wiki/Page_Prev

Linked from the article is the final A/B test they ran: https://www.mediawiki.org/wiki/Page_Previews/2017-18_A/B_Tests https://www.mediawiki.org/wiki/Page_Previews/2017-18_A/B_Tes... They had better metrics than just number of API requests