How do you think the lines are set for the second half?

I have been watching these lines and have made some good money just waiting until half to bet.

If the Favorite is winning by greater than the spread at half then bet the favorite

If the Favorite is winning by less than the spread at half and the 2H line is less than the game spread then bet the dog

There are obviously exceptions to this, but it has been hitting at a strong % since observing.