I find I am logging in perhaps 6 times a day!

Once a day is preferred, never logged out is even fine by me.
Logged out when the browser is closed is fine.

Some sessions can exist as long as the browser is open. If you close a tab on the browser to a site, the access is still there when the site is navigated to again. Close the whole browser and the session ends. Other sites can persist between browser closings. Conversely, sessions can be set to expire based on a time of inactivity. I bet that the vPanel is set to an hour or less!