Large star and combination breaks present a number of challenges, but with a little extra care show the most dramatic cosmetic improvement upon completion.
One thing that is often overlooked is the fact that cracks may extend beyond the edges of a standard curing tab, which can cause a repair to fail. The problem is that even if the cracks are properly filled, they will not be properly cured if not completely covered prior to curing.
Obviously the solution is quite simple. Use multiple curing tabs, or strips of curing film to make sure every crack is completely covered. Run a little thin resin along the surface of filled cracks to help curing tabs stick and properly seal the surface of the crack. One drop every couple of inches is plenty if properly spread with an eye dropper or syringe.
The surface resin may cure in seconds, but it is important to cure for a full 5 minutes to ensure that the resin is cured all the way through. Remember, most windshield are made from a glass that blocks a percentage of the UV rays used to cure the resin, so reducing cure time may cause repair failure.
If the damage is wider or longer than the area covered by your UV light, be sure to move your light as many times as necessary to get a complete cure on every part of the break, curing for 5 minutes each time the light is moved. Long crack lights, dual bulb lights, or multiple lights may be used to reduce the number of necessary light moves.