The flight time is the easy part. The unpredictable stretch is everything between the runway and the room where your meeting happens, and underestimating it is how prepared travelers still arrive flustered.
Build your estimate from the parts most people forget: deplaning, the walk through a large terminal, waiting for a bag if you checked one, the ground transport queue, and local traffic. In big hubs, these add up to far more than the map suggests. Plan for the realistic version, not the best case.
When the meeting is critical, add a margin and use any early arrival to prepare on-site. Walking in early and composed is always better than the alternative.