No way can they keep that small bubble. The first time one of that group sneaks out to see their mistress or goes to hang out at the local gathering place (NZ’s version of 3 times a day trips to Walmart), goes to work or they don’t handle an infected delivery properly, they come back and infect two households.
Not a bubble is what my stupid neighbors just did - party at one house with 15 adults and assorted kids, then days later visiting, with some of those same kids, another house not at the party. That’s how people get sick.
So it’s not going to work for the stupid. But for thinking adults, it answers the problem of lack of social contact at the same time making contact tracing pretty easy.
And, most important, if one of the bubble friends gets sick, the others know immediately and can start preliminary treatment, possibly heading off more serious illness. Remembering our early cases were people who waited until they were on death’s doorstep before they sought treatment, with notsogood outcomes because of the time delay.