A few units at the start of the Autumn Campaign in 1813 could be considered large as they had 900+ men but they shrank to standard after a short time in the field like the rest. By Leipzig there would be a lot which could be classed as small.
Newbury did everything at full strength IIRC. Prussian units were 40 figs at 1:20 and the French 42. The so called 'Fast Play' set have nostalgia value for me as they were the first Napoleonic set I ever owned. Still have them very dog-eared and have been taped together many times.