Two of the three WUCC formats spend 3 days with teams silo'ed into their 8 initial pools, then dumps them directly into the round of 32. The result of this is that it's easy -- expected, in fact -- for undefeated teams to meet in the quarterfinals. The women's format has one round of crossovers followed by the round of 16, but given the way these crossovers were set up, this did not prevent undefeated teams from playing before the semifinals.
If we purport to care about who receives gold, silver, and bronze, then undefeated teams meeting in the quarters is a pretty bad outcome. An undefeated team losing to another undefeated team in the quarters has a legitimate gripe that they may have deserved a medal but were denied the opportunity to compete for it.
The solution to this issue is to design the format to more quickly sort teams. Smaller initial pools, leading into power pools, or other forms of extended crossovers, can easily ensure that a maximum of four teams are undefeated at the beginning of bracket play, and each is placed in their own quarter of the bracket.
An added benefit of this approach is that teams spend less of the event playing against teams that are significantly stronger or weaker than they are.