The Completion Analysis section in the Surveys tab, shows when users most and least often complete surveys in the Fuse instance. In the example below, users typically complete the most surveys on Tuesdays at 1pm. This is the best time to make a survey available on Fuse/share it, as it will have the best visibility and there is a higher likelihood your users will complete it. 

Hover over each block in the chart, to see the percentage of users who have completed surveys at that particular time.

In the example below, 100% of users have completed surveys on Tuesday at 1pm.