Total LT added per unit here is of course singular
Ie firm specific
SASNLT
(Simple Abstract Socially Necessary Labor Time )
Here
is a post facto construct
taking all like concrete labor times together and dividing by revenue from sale of output
The calculation
leaves a historic unit labor cost for a given task set at each stage of value added in production
The market price determines the specific pattern of firm black and red ink
But the actual firm by firm concrete labor times dispersion of the actual output total is by definition social necessary whether the specific LT is above or blow the particular average
You could define a firm using a easily expanded new process as determining the social necessary labor time and show a prospective potential increase in surplus labor time
If market price remained un changed even as all firms moved to the new process
