The charts are generated using user-configured sample intervals. If one-hourly samples aren't granular enough, you can adjust the chart to get more granular samples.
Click on the chart, and it will open a settings page that you can use to adjust the chart settings, including the Sample interval.
It's not the actual chart data I want to change but the frequency of dates/times shown along the bottom. At the moment I'm only seeing the date/time labels 3 hours apart for 'today' and 6 hours apart for 'yesterday'. This makes it difficult to see the precise time associated with a point in utilization. Does that make sense?
Is there a way to allow a pop-up showing the precise time when you hover over a particular point on a utilization chart? The time axis across the bottom is not granular enough, for example if I'm looking at utilization for 'today' the timestamps are 3 hours apart.
The ability to hover over the graph to get an exact data/time for where you are hovering is not functionality that currently exists in the product. There is a feature request that I have submitted to make the graphs more interactive which includes this hover over ability that you are talking about.
If this is something that you are interested in please go put your name on the feature request to show that this is something that you are also interested in. The feature request can be found Interactive Graphs.