Vikings training camp: Why is starters vs. reserves such a big part of workouts?

Gallery: Fans do the Skol Chant at an evening practice during Minnesota Vikings training camp at TCO Stadium.The Vikings' practice on Monday night — held before a capacity crowd in the 7,500-seat TCO Stadium — was their fifth padded practice in seven days, concluding the most concentrated stretch of work in Kevin O'Connell's first training camp as head coach.

"It's just so important for our team," O'Connell said Monday evening. "We've seen the competition ramp up – obviously ones vs. ones in these competitive periods – that's where we're really defining our identity, really in all three phases."

In many of the Vikings' practices, though, O'Connell has included a full-team period that matches…