  We study projective dimension and graded length of structural modules in
parabolic-singular blocks of the BGG category O. Some of these are calculated
explicitly, others are expressed in terms of two functions. We also obtain
several partial results and estimates for these two functions and relate them
to monotonicity properties for quasi-hereditary algebras. The results are then
applied to study blocks of O in the context of Guichardet categories, in
particular, we show that blocks of O are not always weakly Guichardet.
