  This work studies the significance of the lightcurve intrinsic variability in
the numerical modeling of contact binaries. Using synthetic light curves we are
showing that the starspot-based intrinsic variability increases the apparent
mass ratio by $\Delta q=5$%. For systems with orbital period $P>0.3 d$ the
effect of intrinsic variability averaged over long time cancels each other out
with the Kepler Mission-like phase smearing. Further, we analyse 47 totally
eclipsing Kepler Mission contact binaries. We found a sharp cutoff of the
intrinsic variability at P = 0.45 d. With the light curve numerical modeling
and observational relations we derive physical parameters of the 47 systems. At
least 53% of binaries have a possible third companion. 21 binaries show the
O`Connell effect in the averaged phase curve. 19 of them have a primary maximum
lower than the secondary, suggesting a stationary dark region on the trailing
side. Using the P = 0.45 d cutoff we propose a new approach on the Period-Color
relation. The only parameter correlating with the magnitude of the intrinsic
variability is the apparent effective temperature ratio. We conclude that
instead of describing the system parameters, the A/W-subtype division should be
applicable only to the lightcurves, as a tentative phenomenon.
