It's not useful. Indeed that's likely why we die of old age - there is no selective pressure to remove harmful mutations that don't reduce your ability to pass on your genes so such harmful mutations just accumulate over many generations. You might have a mutation that will cause your heart to rupture at age 150, but you'll never know it because you'll die of something else first.

It is possible though to selectively breed animals like flies for long lifespan. You wait to see how long one generation lives and cull the descendants of those that died early. It's inefficient but lifespan extensions of 50-60% have been demonstrated. One could imagine through gene editing that a species might be able to reap the benefits without the culling.

https://pubmed.ncbi.nlm.nih.gov/3113991/