  For multilevel spin systems, robustness of the quantum mechanical (QM)
violation of macrorealism (MR) with respect to coarse grained measurements is
investigated using three different necessary conditions of MR, namely, the
Leggett-Garg inequality (LGI), Wigner's form of the Leggett-Garg inequality
(WLGI) and the condition of no-signalling in time (NSIT). It is shown that for
dichotomic sharp measurements, in the asymptotic limit of spin, the algebraic
maxima of the QM violations of all these three necessary conditions of MR are
attained. Importantly, the QM violations of all these persist in that limit
even for \textit{arbitrary} unsharp measurements, i.e. for any non zero value
of the sharpness parameter characterizing the degree of fuzziness of the
relevant measurements. We also find that when different measurement outcomes
are clubbed into two groups for the sake of dichotomising the outcomes, the
asymmetry/symmetry in the number of outcomes in the two groups, signifying the
degree of coarse graining of measurements, has a crucial role in discerning
quantum violation of MR. The results clearly demonstrate that classicality does
not emerges in the asymptotic limit of spin, whatever be the unsharpness and
degree of coarse graining of the measurements.
