On nearly level terrain the peloton has a distinct aerodynamic advantage that lets them reel in most people who are just having a good day. People try it anyway and hope for bad luck, or leverage time bonuses if the rules allow it.

Big groups on a downhill are dangerous, on an uphill are too hot and cramped and so in both cases individual skill and power are outsized. If a technical downhill racer can break away on the last climb, they may be gone for the day. Tours have been lost or won on this tactic.

In a multi day tour a twelfth place competitor might pull away, even take a few people with them. The other teams may not be interested in catching, might have lesser members in the breakaway and be hedging their bets, so they can’t build consensus on burning their people to kick up the pace. They make think that they can wait for him to wear out and reel him in later, but there comes a point where from one update to the next they discover he’s still gaining on them, and oh shit do we still have time to catch? We better find out.

The worst for me is when they catch the breakaway mere miles from the finish line. Sometimes a person stays away all day only to end up finishing in the group, or at least beaten by all the sprinters.