This audit ensures that ads take up no more than 30% of the page vertically. A ratio greater than 30% has been found to negatively impact user experience.
Depending on the situation, slots should either be spaced farther apart or have a reduced size.
On mobile devices, we assume a single column layout and so all ads on the page are included in the ratio calculation. On desktop, we divide the page into multiple vertical slices to account for multi-column layouts. The audit measures the ratio of ads to page-height in each slice individually to ensure no individual slice exceeds the maximum recommended threshold.
To account for lazy loading, we measure content length up to 1 viewport past the last ad. To measure the ratio over the entire content, disable lazy loading.