Engine belts are a wear item much like tires or brakes. Much like our techs can see indicators prior to failure of those components our tech too can see indications prior to drive belt failure-fraying, rib splits, noise, stretching, cracking etc all may indicate replacement time. No one wants to suddenly loose power steering on the highway or loose power assisted braking as found in many General Motors hydroboost systems. Further once the belt brakes the sole item powering the ignition components on coil on plug and other electrical systems will be left to the battery. Baring that drive belt failure can wreck havoc to engine bay components.

Sure. First we will ensure the correct belt has been installed, check tensioner(s) for proper operation then inspect related pulleys for wear- idlers, alternators, fans, water pumps, power steering pump, a/c condenser etc.