Whether or not it's worth it to repair the blow head gasket on the vehicle will depend on the value of the vehicle.
If it's an older vehicle then it's likely not worth the cost to repair the head gasket as it can cost $1,000.00 or more to replace the blown head gasket.
It can take a good shop around 2 days to replace the head gasket because they have to remove the top heads off the engine and other things that are in the way and then reassemble it.
If it's a newer car then it may be worth the cost to replace the head gasket that is blow but then again the blown head gasket could've caused other problems with the engine.
Sometimes it may be cheaper to replace the whole engine in the vehicle or even buy another used car for the cost to repair the blown head gasket.
You can replace the blown head gasket yourself if you know what you're doing but it is a time consuming job.