I am confused about where you are seeing that SB was heard from on Friday afternoon. On SB's sister's (EM's) FB dated December 4th, she says this (via someone else, whose privacy settings are set so that we cannot see her posts) (BBM). If people are saying she hasn't actually been 'heard from' since Wednesday, perhaps some are not taking at face value the husband's assertion that he last 'saw her' just after midnight that same day (which by 12:30am had become Thursday):
Erin Madill via Meghan Cooper
December 4 at 12:40am ·
Shannon H Burgess is still missing and hasn't actually been hear from since Wednesday. She was actually last seen in Calgary not Edmonton though she does have contacts in Edmonton as well.
Again... it is wording. The last time SB was SEEN was on the 27th. The same sister in MSM was the one who posted that they last HEARD from her on Friday. If that additional communication was in the form of a text or PM, then it is not considered being SEEN. Given that there is no way to prove that the person who sent a digital message was SB, they have to go off when she was last physically seen.