Where I currently work, the SOP is NOT to specify the direction of evac. It's up to the Cabin Crew to assess whether a particular exit is safe to use or not...
The CC are 'on spot' for every exit, while the pilots sit up to 200 ft forward, so IMHO the CC are better suited to decide.
PLUS, while specifying direction, there's an added potential for left/right-hand confusion eg. for aft-facing CC's