Currently, the buckets' size varies depending on number of days being displayed in the report. As a result, the reports are not comparable.

This is quite obvious when selecting a "to date" period (e.g. YTD, this quarter, this month, etc.) and today's date is early in the period. For example, selecting this quarter on Oct 21st, we get daily buckets as expected, but the same report shows hourly buckets instead when executed on Oct. 3rd.

For a given period, data should always be aggregated in the same way.