Usually at college/highschool meets, you have a good/decent idea of what kind of competition you're facing, so you know no one is going to get away from you (at least based on your heat). What happens in an open race where they may not segregate based on heats?
The situation is: You probably don't know anyone there. Each All-comer's meet probably has new sets of runners, very few regulars. The question then is...if person x takes off on you...do you let him go assuming he is just an over exuberant teenager or do you hang on as long as you can?
I have seen old farts that look slow that have blazed..guys that have looked fast go slow...it's hard to judge your pre-race plan based on any assumptions. All-comer's meets can be a mixed bag, never know who will show up and blaze.
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