Depending on the characteristics of specific fires and locations, that might be too much, not enough, or simply the wrong tactic.
In the Camp and other recent fires, most structure losses were precipitated by blown embers, rather than direct exposure to a flame wall. In many places, the ember plume resembled a rain or constant stream, rather than individual embers or firebrands floating through the air, and any point of purchase or entry (dead leaves, brush near the house, exposed eaves, raised wooden decks or stairs) were potential ignition points. Embers entering into attics through eves seem to be a particularly pronounced factor.
A firebreak of ~100m is sufficient for most instances, if construction is fire-aware and flammable litter is kept to a minimum. Features such as sprinklers can also help -- even a small amount of water will keep surfaces below ignition point. (Though there can still be other heat and smoke damage to property and possessions.)
What's increasingly occurring in California is a merging of wild and urban fires as occurred in Ventura, Paradise, Sonoma, Santa Rosa, Glen Ellen, and Redding in recent years. These are major conflagrations not at the urban-forest interface, but well within urban zones. Fire safety zones enough are proving insufficient in such cases.
Quite sane norm, given that firestorm can leap 500 metres and give instant radiation burns at a substantial distance too. Poisoning is also a big threat.
Look at norms in other countries with hot and dry woodlands
The few states in US that have a recommendation on that put safety zones of just 150m or less