Damage to windshield glass can be very unpredictable. A small chip from a rock may not spread for ten years, while another small chip may grow into a two-foot-long crack in 30 minutes. But the good news is that even if your windshield is severely cracked, it will not randomly shatter or cave in on you. Only an extreme impact from something like a brick or a wreck can cause the glass to do that.
If there is a crack directly in your line of view, we do not recommend continuing to drive the vehicle. Even if the damage is minor and repairable, if it is in the driver’s direct line of vision, insurance companies require windshield replacement.