In cookie making, Does creaming time change with the amount of butter used? i cream 40  grams  of  butter  with  50 grams  of  sugar    for  2  min. i get  good  results. if  a cream  double  these  amounts,   would  the  creaming  time  change?  thank  you
Yes, larger amounts will take longer to cream than smaller, how much time that really means depends on how you are creaming it. If you are using an electric mixer of some kind then I would expect the difference in time between 40 grams of butter and 80 to be pretty small as 40 grams or even 80 grams of butter isn't much. 

I wouldn't use time as a guide to creaming butter and sugar, the times given in recipes are guidelines and vary depending on conditions and equipment. Butter and sugar are creamed properly when the mix gets pale and fluffs up, expanding to nearly double its size, this may take more or less than 2 minutes.