Comment by happytoexplain

Just to add the the anecdotes: In my experience over ~20 years flying out of Newark and Philadelphia, 1 hour is enough 75% of the time, 2 hours is enough 95% of the time, and 3 hours is enough almost 100% of the time (I have once had three hours go by from walking through the front doors to the gate). That doesn't mean you always show up 2 or 3 hours ahead though - you adjust your estimate by time of year, time of day, and international vs domestic.