Here, you define what data will be included into a chart.

We strongly recommend you to use the scheduling mode by task start as scheduling by task end may significantly slow down a chart generation.

If scheduling mode is set by task end, planning by whole days is strongly recommended. Planning in hours and minutes may lead to incorrect app behavior.

To summarize, this option allows everybody to see a chart like the impersonation person does (even though, viewers might not have have the required Jira permissions).