Depends on situation and conditions. In this UX case, assuming that information is ready, a team of 10 UX experts with similar expertise and have been working together for some time will reach the good decision.
A team consist of CEOs, managers, devs, UX, marketing/sales & finance won't get the same level of decision assuming the information is ready. However they'll be useful for information / idea gathering / brainstorming when the information is not ready, for a single person / team to make decision.
My past experience sums up to this:
* Team of similar expertise & knowledge: good & fast on decision making, lack on seeking knowledge in other part of expertise
* Team with variety of expertise & knowledge: will make slow & bad decisions more than good or fast one, in exchange of decent chance of knowledge sharing for each expertise
Of course the quality of each member, how can they work as a team, whether they have hidden personal agenda / hating each other plays part in the quality and speed of decision making too
"Researchers have compared the strategic behavior of groups and individuals in many games: prisoner's dilemma, dictator, ultimatum, trust, centipede and principal–agent games, among others. Our review suggests that results are quite consistent in revealing that group decisions are closer to the game-theoretic assumption of rationality than individual decisions."
Do you believe that there is a single right answer to your question, so that teams always make better decisions than individuals, or alternatively always make worse ones?
I'd say teams are way more likely to avoid clearly bad decisions.
Now your statement is so clearly absolutist in its tone, so to speak specifically, I would say teams will largely point to the best outcome eventually but often pays the bill in over lost efficiency.
Individuals make bad takes, sometimes they have personality issues, sometimes then have a terrible day and are dialing it in at work who knows. What I know is that it's less likely that an entire team are living their worst day at the same time which could lead to catastrophically bad decisions.
