3 Mbps/household is enough for evening streaming, statistical multiplexing kicks in as the number of subscribers grow. It's a bit naff, but not overly so.

Averaging 3 Mbps of usage does not mean the gigabit connection drops down to 0.5% nightly. The key here is for the ISP to have enough excess backhaul to account for the occasional burst above the 3 Mbps average. As long as there is sufficient headroom, nobody will notice the oversubscription.