There's always going to be an element of risk to killing women, whether in the street, in a back yard or in someone's room. The ripper avoided being caught though and so we have to assume that he exercised caution to minimise those risks. If he hadn't have done that then we would have to put his avoidance of capture down to luck (and lots of it.)
"There is nothing more deceptive than an obvious fact!"
Now, here's a rather more complete version of Ms Farmer's inquest evidence than one finds in the Times.
From the Star of 10 September:
"I am afraid deceased used to earn her living partly on the streets. She was a very straightforward woman when she was sober, clever and industrious with her needle; but she could not take much drink without getting intoxicated. She had been living a very irregular life all the time I've known her."
“The supposition finds ready acceptance that the poor woman was murdered outside and taken into this yard, by those who knew the place well. This is upheld by the fact that spots of blood are lying thick in the narrow passage leading from the street into the yard, and the blood marks where the body was found must have been caused by its being deposited there, there being no signs of any struggle having taken place in the vicinity.”
Were the 'spots of blood' in the passage noticed before the body was removed or after? If after, the spots if 'thick' (presumably congealed) could have been deposited during the removal process surely?