More than 2 years after I baked my Sapphire R9 270X for the first time the thing still works. In total I baked it 7 times since June 2019:
1. June 2019 - 190°C/8 minutes - worked the longest period of 8 months
2. February 2020 - 200°C/10 minutes - worked only month and a half
3. May 2020 - 200°C/15 minutes - worked 6 months
4. November 2020 - 210°C/12 minutes, worked just few days
5. November 2020 - 220°C/15 minutes, worked 6 months, but it crashed several times, but it would work after reboot
6. April 2021 - 210°C/15 minutes, worked 3 months
7. July 2021 - 200°C/15 minutes, worked just a month
8. August 2021 - 210°C/15 minutes, to be continued...
As you can see the poor thing doesn't even have its original fans. One fan became noisy so I removed it and put one of my case fans which I connected directly to PSU with a molex at 12V. In worst case so far it reached 78°C, but that is still under control, since it only happens in summer when my room is warmer.