The target time for an emergency evacuation is 90 seconds.
And the manufacturers must demonstrate that this is possible in order for the aircraft to get certification.
[0] My use of the word "just" should betray the fact that this is far more complicated than I think it is. Obviously, this would be too expensive, impractical, and double the weight of the aircraft all to solve a very minor traveler issue.
If you're thinking of using two front exits, jet bridges also can't get too close to the engine so the only narrowbody that works for is the aging 757. Plus it doesn't really save time because the space between 1L and 2L is generally first class.