Its usual these days for any hard wired cooker to have its own circuit breaker - but in days gone by they were wired into the kitchen ring main. Either way, if a fault developed the breaker would still trip, maintaining safety. Theoretically, the more individual circuits your house has, the better for fault finding and isolation etc and the less chance there is for overloading, so its best to consult your local building regulations people for their advice.
John, May 2009