The node monitor tracks the status and performance of your node, your minting account and some Qortal network statistics in real time. It does not store any of these values, to store values you should use the ReQorder feature.
When your node is synchronized, the node monitor does a refresh (pings the Qortal API) every 60 seconds. You can manually refresh the values every 10 seconds by clicking the 'Refresh Now' button.
When your node is not synched (your blockheight is lower than the Qortal chainheight), the node monitor will refresh every 10 seconds until it is synced again, at which point it will set the refresh cycle back to 60 seconds.
When out of sync, the monitor will start estimating how long it will take to get back in sync. It does this by obtaining the block syncing rate and relating that value to the number of blocks left to synchronize. This means that it needs time to gather some data in order to make an estimation and that the estimation is based on the average syncing rate since the node went out of sync. Leaving the node monitor by using the taskbar and then clicking 'Node monitor' again will restart the estimation. Note that if your blockheight does not increase, an estimation will not be available and the monitor will display 'Estimating time left' until your blockheight increases.
The node monitor does not automatically fetch or refresh QORT prices relative to other crypto currencies. This is due to the time delay caused by fetching prices from the Qortal API. You can fetch the prices manually every 2 minutes by using the 'Fetch prices' button at the top of the node monitor. Note that ReQorder fetches the average price based on the last 10 trades in the Qortal trade portal.
If your node is not running or your SSH tunnel is not connected to a remote node, the node monitor will not be able to access the Qortal API and thus not function.