Going of ver recommended TBO

Hello All,
Where I fly, the density altitude on the tarmac is typically more than
7000ft even on cold days (9000ft on hot days). As a result, non-turbo
engines cannot develop any more than 70% of rated power.

The consensus around here is that as long as the engines are blessed by
the mechanics and checked for compression, one can exceed the
recommended TBO sometimes by a factor of 2x.

My question is this: Is this practice safe? What about material fatigue
in the engine components (i.e. crank shaft, pistons, rods, valves etc)?
Would this practice make the chances of an engine failure more likely?

Thanks.