The phrasing of the Medicine skill is a little vague. Specifically, this part:
...a character may attempt only one Medicine check per week when helping a character to recover from critical wounds.
The entry under the Recovery and Healing section doesn't help either:
A character may attempt one Medicine check per week per Critical Injury.
The problem is, this implies that if someone has a Critical Injury, every other character in the group can make an attempt to fix it — that if someone fails, someone else can step in and try it themselves.
This just makes me think of how President Garfield suffered for 80 days under the unwashed hands of clueless doctors before finally dying.
Am I right in assuming that this is supposed to mean that a character with a critical injury can only be treated once a week, no matter how many people are present?