Faithful Latter Day Saints enjoy cohesion and order in their religion, and barring the exotic scheduling of low LDS population densities back east, and the high LDS population densities in Utah, if you are Mormon, you go to church at either 9am, 11am, or 1pm. While there is some room for debate in terms of personal or family taste, the 9am block schedule remains the most popular time for Saints to gather to worship. This largely is based on the unofficial family rule that piety and spiritual activities should be observed at least until after church. With the 9am schedule, piety and spirituality are squeezed in between bowls of Cap'n Crunch and Lucky Charms and the whirlwind rush to prepare 4-9 small children for church. After a refreshing dose of spiritual nurturing at church, happy families rush home in time to catch the next showing of RV starring Robin Williams on TBS, or even an entire NFL game in the afternoon. Those unfortunate souls who must endure until 1pm struggle to find nourishment beyond a marathon of Living Scriptures VHS tapes, re-runs of Veggie Tales, and a healthy dose of old EFY or Kenneth Cope albums.
The unofficial ending point of most fasts on fast sunday? Ask the average Saint, and they'll tell you enthusiastically "Why, after church of course!" Enthusiastically, that is, unless they have to endure the crucible of fasting until 4:00pm. The 9am block offers a snack size bit of fasting for faithful Saints, the 1pm block, a gruelling test, likely to actually yield spiritual benefits.
The 9am block also has other benefits. For example, at that early hour, it is almost expected that families with small children will arrive 5-10 minutes late, MST, or Mormon Standard Time. At the 1pm block, those same families will still arrive 5-10 minutes late, the difference being the occasional chastisement they will recieve from the bishopric. "We encourage our ward members," the bishop will say "to try to arrive at our meetings on time. It's not as though we are meeting during the 9am block."