When meditating and practicing in a group, if I am feeling settled and grounded myself, it does not disturb my practice that others near me are fidgeting or not fully present. Just as I can meditate on a bus or in a waiting room, I am responsible for descending into my own inner space. If I am unsettled myself, then I am more likely to notice others fidgeting. But it is not their fidgeting that disrupts my practice, but that I am having a day when it is hard for me to center on my own.
It is true, though, when practicing with a group, that sometimes we will all be deeply centered and then the power of the group can bring all of the individuals to a deeper experience.