No, orathaic, no evidence, just what I believed was my experience. Of course my observation of my games is tainted by my presence in those games so isn't fair to extrapolate on everyone else.
Leagues Fall/Autumn 2012:
A*: 1912, 1913, 1911, 1915, 1914, 1915, 1911
A: 1908, 1912, 1909, 1912, 1912, 1906
B1: 1909, 1918, 1912
B2: 1913, 1912, 1909, 1912
B3: 1912, 1908, 1910, 1908
C1: 1913, 1907
Leagues Winter 2011:
P: 1911, 1911, 1919, 1918
A: 1911, 1915, 1918, 1911
B1: 1910, 1911, 1912, 1912
B2: 1910, 1915, 1910, 1908
C1: 1918, 1911, 1913, 1921
C2: 1908, 1915, 1907, 1909
C3: 1915, 1914, 1915, 1909
D1: 1909, 1908, 1908, 1907
D2: 1913, 1912, 1915, 1913
D3: 1909, 1909, 1917, 1916
I'm not a statistics knowledgeable person so don't know how to evaluate that.
But, looking back over my own games for the previous season, it appears I'm just full of shit with regard to my theory on the later games lasting longer.