As long as nontrivial human reasoning is a necessary part of the process, even if it's a small part, the process as a whole will stay at least somewhat "anchored" to a human-tractable time scale. Progress can't speed up past human comprehension as long as human comprehension is required for progress. If the human bottleneck goes away there's no guarantee that other bottlenecks will always conveniently appear in the right places to have the same effect.