Time spent in phases of cell cycle
This is the data for a few cell types:


Cell type   Total      G1      S      G2      M      Ref
----------------------------------------------------------
Neuro2a        9       2       5      1.5    0.5     [1]
Hela         16.2     7.7     7.2     0.8    0.5     [2]
A549          18       7      7.5     2.5     1      [3]
MCF7         21.3      9      9.3      2      1      [4]
CHO           15       6      6.8     1.2    0.65    [5]


The timescale is in hours. 


References:


De Laat et al. 1980
Kumei et al. 1989
Orfanoudakis et al. 1989
Taylor et al. 1983
Harada and Morris 1981