What's interesting is the 50% vs 80% reliability gap. At 50% success rate on a 4-hour task, you're essentially gambling. If it fails, you've potentially wasted the 4 hours plus the time debugging why it failed.
This is why I think the current "agent" paradigm needs human checkpoints at regular intervals. Let the AI work for 30 minutes, then review progress. Repeat. This way you catch drift early before it compounds.
The other thing missing from these benchmarks: recovery ability. When the AI gets stuck on hour 3 of a 4-hour task, can it recognize the problem and backtrack? Or does it confidently continue down the wrong path?