ahh, I get it. I am no expert, but I don't think there would be a time difference between the two. Reason being, I notice that the carbonation blows off if I pull down a beer the same day, but doesn't if I wait 2-5 days. I assume it takes time for the CO2 to bind with the beer molecules due to the presence of alcohol. Therefore, my guess is that on the molecular level, the time needed for carbonation is the same no matter the volume of beer.
Shaking is highly recommended, it appears the CO2 is absorbed much quicker.
Just an opinion, I'm sure there are others that may know more.
PS. Experience with Soda's are totally different due to the lack of alcohol.