From the TD end, in making this decision, you have to consider logistics and player preferences.
Logistics such as finishing in daylight, unforseen delays (good point, Dave), weather, etc.
Player preferences are tougher because they're all over the board, and we're guessing. Some prefer later starts (especially those who might have been out late the night before), some earlier (especially those with families and other reasons to get home as early as possible). Furthermore, players at any given tournament can be divided between locals, commuters (say, 1-2 hours, driving home at the end of round 2), and out-of-towners (whether staying overnight just Saturday night, or Friday & Saturday). Multiply these together and everyone has good reasons for wanting different start times.
Logistics such as finishing in daylight, unforseen delays (good point, Dave), weather, etc.
Player preferences are tougher because they're all over the board, and we're guessing. Some prefer later starts (especially those who might have been out late the night before), some earlier (especially those with families and other reasons to get home as early as possible). Furthermore, players at any given tournament can be divided between locals, commuters (say, 1-2 hours, driving home at the end of round 2), and out-of-towners (whether staying overnight just Saturday night, or Friday & Saturday). Multiply these together and everyone has good reasons for wanting different start times.