I always service my car every 3 months, I would think to wait till something go's wrong? is crazy.
You have to have the oil changed anyway every so many months, and they look at all the other things, like points..spark plugs...tyres...ect etc.
I am not really on the road too much, but you have to look after the car.
I don't think there is much point in spending money on getting your car serviced unless you know it is needed. Get i checked out on its yearly MOT and it should be fine. If you are someone who gets a lot of road miles, perhaps it will need more, but for the average user, once a year should be enough.
I usually get my car serviced every 4-5 months or before a major road trip. For peace of mind I have also recently taken out an extended membership with NRMA in case I ever break down in another town or state.