I'll pull all day long at 16-19.

Pulling a mile seems stupid to me. Defeats the purpose of a pull and becomes a contest. That would result in a slower group. Unless you've got a Cat 1 and the rest are Cat 5's.

At our small group ride, I'll pull for 30 seconds or so. Less when the pace increases and I feel that I can't pull longer without blowing up. For me, it's all about working together as a group. Pull for just a bit at very hard effort, then get off and let the next guy work while you rest. This way the pace line doesn't slow down as much.