Speaking of sizing, I have worked with the smallest cluster space being 18mx 18m or 60feetx 60 feet. Where the ambience is one of a courtyard, with 9-10 homes around it. The treatment of the courtyard is best with a single element, like a tree or a waterbody, to give it a sense on oneness. A mid-sized cluster space would be 25m x 25 m, with more homes around and the space in the centre being used for play and community activities. Larger spaces become playgrounds, where the homes are far enough to avoid windows being broken by enthusiastic cricket players hitting a six. Street planning which also breaks the monotony of a straight line, by introducing small wider clearings intermittently, which may become wayside sitting places, especially for the elderly. Transitions to and through these clusters, become character defining elements. These explorations have been in the context of low and mid-rise development, but the possibilities exist in the high rise too.
If one can think alternatively that the shared spaces are as important as the personal, and need a joint caring, in terms of time and priority, we may see our neighborhoods changing.