This is why it's usually impossible to get good data access inside stadiums during games with thousands of people clogging the network. This theory of network data congestion holds true with too many people accessing data on the same cell tower. Everyone is competing for the same access on the cell phone tower and the tower only has so much capacity. The more people accessing data on a cell tower, the weaker the signal. You might notice the strength of your cell signal in a certain area change depending upon the time of day because of rush hour or you are near a heavily populated area.
This is one of the main reasons why many Verizon customers have suddenly started experiencing a lack of coverage in areas that they previously had 3, 4, or 5 bars of signal strength. Coverage is not guaranteed and coverage maps don't really mean much these days. It's up to you to submit your coverage complaints to our map where you experience frequent poor coverage. Deadcellzones.com seems to be the only service that is trying to hold carriers accountable for coverage the promise in areas.