Influencing Groups Means Influencing Individuals
Groups and individuals are the yin and yang of influence. To convince a group often means convincing individuals. And convincing individuals often means convincing a group. Knowing who to focus on, and in what setting is the key question we have to answer when we want to affect a decision.
Getting a group to agree on a course of action can mean taking one-on-one time with different members of the group, or meeting in a smaller group. And sometimes, convincing an individual needs the social proof of group support.
As you work towards a particular outcome, you may switch between group and individual interactions over time. The exact mix will depend on the situation, and especially the decision making styles, issues, and authority of those involved.

We can also visualize what one set of interactions might be, as you meet with a group, and then individuals one one one and with members of the group in a smaller setting:

This is just a hypothetical example of how those interactions might play out over time as you work with different people in the group. The key thing is recognizing when you can make progress as a group, and when you should reserve your efforts for smaller or one-on-one conversations.