Thank you for your post.
With respect to strangulation, I don't think it is safe for anyone to assume that unconsciousness from strangulation occurs in 10 seconds or less. It depends. Refer to attached which states with complete and sustained obstruction of both jugular veins, it takes approximately two minutes to full unconsciousness and another two minutes of sustained unconsciousness until death occurs.
As far as I know, it is unknown whether CW applied pressure to the carotid arteries or to the jugular veins and it is also unknown if that pressure was complete and sustained from the moment he began strangling Shanann.
JMO, the lack of defensive injuries to both Shanann and CW does not necessarily mean that she was unconscious before she knew what was happening. It could mean that she was restrained and unable to try to defend herself.
http://www.napsa-now.org/wp-content/uploads/2012/11/102.pdf