Individual vs collective decision making

I often see a call with lots of participants discussing a solution. Is it efficient?

Let’s break a process of finding a solution to a problem into pieces. We need to do the following steps:
1. Find the root cause of the problem
2. Find possible solutions
3. Choose the most efficient solution
4. Ensure decision making process was objective

Do we need many people in these steps?
Many voices give many options. You need tons of time and effort to find the solution and you won’t find it - you will find a compromise that is least bad for all but not the most efficient option.
So a compromise in steps 1 and 3 break the whole idea.

However many voices can give many possible solutions. This is good.
Also a second pair of eyes easily checks for objectivity, the thing an individual can miss until he has dissociative identity disorder I

I’m sure steps 1-3 should be performed by a single person and step 4 - by another person.
Step 2 can be a collective effort (i.e. brainstorming) if the author experiences difficulties finding possible solutions.
What do you think?