It is important to get the orientation right for the garage door torsion spring replacement exercise. This basically means that the right hand wound spring has to mount on the left of the center. Most installations have one on either side. The replacement is most likely to occur after 10,000 cycles. How one gets there is largely due to the nature of the usage. It is estimated that daily use of up to three times a day is likely to allow the door to function for nearly a decade.
On the other hand, the increments in temperature can change this calculation and some have estimated that it shaves off as much as half of the spring life. In any case, deterioration occurs when the wire crystallizes and snaps at those weakest points. If it is a two-spring system then both ought to be replaced in tandem. This is one of those situations where the problems on one side will most definitely affect the other.