Depends Nands, some have 4 lights all powered by a 10000w bulb, these bulbs are very expensive though and a more popular method is for the house to have 100 bulbs on each side, that is very time consuming though as if one goes its a bugger to find which one to replace.
Few more years though and everyone will be on to the modern lazor fiesta XR2 lights which can be fitted, worked remotely and have a lifespan of 25 years.
I can normally change the bulbs on me own, but I prefer if somebody is there to hold the ladder.