Hard Disk Monitoring

If the detection frequency is set to 5 minutes, should the temperature chart update every 5 minutes?

Yes, the temperature chart is updated when new status information is detected (following the detection frequency).
Also it may be updated on manual updates and/or more frequently if you start a hard disk test from the Disk menu.

I had to completely exit HDS and restart it for the change to take affect.

Also, now as I try to adjust it, I have to focus on another control 'after' moving the slider in order to see the value updated. *correction* I just had wait 4 seconds for the value to update.

As you may notice, when the silder is moved, it triggers Hard Disk Sentinel to re-detect the hard disk status information.
In some situations this may take some seconds and the information is updated only after this process is completed.
Sorry for this delay.