We don´t really know that. This is all we can see of the blood - we have no photos of the spot of blood without the bible on top of it.
Sheila may have sat up for the first shot and been in a lying position for the second.

The large stain at the top was formed by it being placed in a pool of blood. That is not a drip stain.
She would have fallen back from either shot so had to be propped up against something during the course of the first shot.
Moving away from whatever she was propped up against so she could lay down would have resulted in much more blood leaking down the side of her neck onto the floor. Trying to open the bible and read it while lying down is ridiculous but worse it would not result in bloody drips that could only happen while she is above the bible. So we are supposed to believe she was initially shot seated propped up against something, opened the bible at that point dripping on it, then moved her body away from whatever she was propped against to lie down and got blood on the floor, still had the bible with her and opened it while laying down to put next to her shoulder and then shot herself while lying down.
The blood evidence doesn't support such nor does common sense. Modern blood staining evidence says she was shot while seated and then moved flat after her death. She would have put down the bible by her side not move with it in her hands so she coudl drip on it and then lay it next to her shoulder.
She was flat so he could lay the gun on her, he couldn't lay it on her while she was propped seated so tha tis why he moved her body. After he did so is when he decided to move the bible to make it appear she read it while lying down right before she fired the second shot.
Vanezis said both shots were fired within seconds of one another. She would not have had enough time to read the bible, then move her body flat then read it again and put it down next to her shoulder and then to carefully plan another shot.
It is even more inconceivable for her to lay down with the gun on top of her and no GSR ot get on her gown. Gravity would pull the particles to her gown. It already is unlikely that she could have hugged the gun and GSR to not get on her gown but laying down with it on her is worse then for sure GSR would be expected.
That is without even taking into account the moderator and physical evidence that she didn't kill the others.