Yes the more in focus the less likely they moved during the long exposure [rigor mortis]!!
I dont think its particulary crazy they were surrounded by death alot mortality rates were really bad and this was a cheaper way to remember the dead rather than huge portraits they also liked taking hair and turning them into pictures !!!
And in Heather's case, there were sometimes Third Thoughts and Fourth Thoughts, although these were quite difficult to manage and sometimes led her to walk into doors