  The Vera C. Rubin Observatory will carry out its Legacy Survey of Space and
Time (LSST) with a single-exposure depth of $r{\sim}24.7$ and an anticipated
baseline of 10 years, allowing to access the Milky Way's old halo not only
deeper, but also with a longer baseline and better cadence than e.g. PS1 3$\pi$
(Chambers et al. 2016). This will make LSST ideal to study populations of
variable stars such as RR Lyrae stars (RRL). Here, we address the question of
observing strategy optimization of LSST, as survey footprint definition, single
visit exposure time as well as the cadence of repeat visits in different
filters are yet to be finalized. We present metrics used to assess the impact
of different observing strategies on the reliable detectability and
classification of standard-candle variable stars, including detection of
amplitude period, phase modulation effects of RR Lyrae stars, the so-called
Blazhko effect (Blazhko 1907, Kollath et al. 2011), by evaluating metrics for
simulated potential survey designs. So far, due to depth and cadence of typical
all-sky surveys, it was nearly impossible to study this effect on a larger
sample. All-sky surveys with relatively few observations over a moderately long
baseline allow only for fitting phase-folded RRL light curves, thus integrating
over the complete survey length and hiding any information regarding possible
period or phase modulation during the survey. On the other hand, surveys with a
cadence to detect slightly changing light curves usually have a relatively
small footprint. LSST's survey strategy, however, will allow for studying
variable stars in a way that makes population studies possible.
