To the extent that [MENTION=23935]Nagol[/MENTION]'s Ars Magica example is meant to be a negative example, the issue would seem to be one of pacing.
WIth the Champions example, again to the extent that it is meant to be a negative example, the issue would seem to be that the one player was able to make a choice that resolved the stakes for the other players. I think that can be a big issue, especially in systems that assume group play and so group win/loss.
Neither were about pacing.
The Ars Magica campaign had about a 5 minute conversation with the lady before one player got antsy and worried the person on point was being too circuitous as opposed to the other players who thought she was being careful and delicate, as urged.
The CHAMPIONS campaign the players were aware of the danger to several PC loved ones. The group had decided a direct frontal assault was too risky and spent maybe three minutes working out a plan when on player decided that's not an approach his character would take and he unilaterally did the whole out in the open call out.
Both were about one player trampling on the agreed approach for the group. In effect, as [MENTION=177]Umbran[/MENTION] put it: "There are times when players are trying an approach, and are frustrated, or it rubs them the wrong way. They say "screw this," and do something else."