A lot of people aren’t aware of the response time of their sensors and how it has an impact on this. If you have big, 5 mm diameter tips on the thermocouples vs a 1.6-2.5 mm tips, you will have a multi-second time constant. This means that if you for from 330 °C to 900 °C when stepping on it, you can be waiting 5-20 seconds before your ECU actually knows you have 900 °C EGTs. Furthermore, a lot of people do not distinguish between peak temps and sustained and that has a major impact on what the temperatures mean.
It takes time to saturate the components of a turbo with these temps. If you blip to 900 °C for 2 seconds but bring that back to sub-800, then you’ll be *generally* fine. As you said, you’re in the mountains so it is easy to have high, sustained temps, which are simply unavoidable. The newer generation turbos cope better with this.