Having had a FT817 PA+driver fail due to feed line problems (intermittent open in RG174) I absolutely always leave the rigs showing the SWR display. During setup I’ll have a look at the power out but then it’s back to SWR. I run the 817 in the full display mode where you can also see the battery voltage. This is always less than the actual battery voltage at the terminals.
In operation when transmitting I actually observe the voltage and SWR to ensure everything looks kosher. As soon as the slightest thing looks wrong I stop TXing and check. Checking the voltage stops me hammering the LiPo into oblivion. Still using the same LiPos bought in 2009.
You only have to blow up one PA to learn to operate in an alert state!