Right now there are reports of super-high early first-day voter turnout in FL. FL voting ends at the same time as PA. If either FL is called early due to a clear landslide, or if PA gives Romney an early significant lead in Romney votes whether called or not, a significant effect could occur as other states with votes not yet cast rapidly redden.
Which would give the MSM an incentive to hold the data in spite of the competitive pressures.