There is an optimum somewhere on the line. Even if you have 5 people for 30 min on the call, it's totally understandable that one or two of them find it mildly

There is an optimum somewhere on the line. Even if you have 5 people for 30 min on the call, it's totally understandable that one or two of them find it mildly boring but here and there relevant. For instance they are expert in one of the field touched by your project and they sometimes need to react. In your ideal state, the choice is for them to leave the meeting altogether and find something else they can focus more on, or to focus 100% on the meeting and spend half of their time religiously listening to stuff they don't really need to hear. In my experience the result of the second choice is people being more and more reticent to come to meetings, not just because of some hypothetical time lost, but because it's mentally painful. As an added bonus, instead of having one meeting with 5 people, you need to make 3 with only the parts each members fully care about, and eventually a few more down the line when what they each say in isolation doesn't make sense when assembled together.