  With their emission mainly coming from a relativistic jet pointing towards
us, blazars are fundamental sources to study extragalactic jets and their
central engines, consisting of supermassive black holes (SMBHs) fed by
accretion discs. They are also candidate sources of high-energy neutrinos and
cosmic rays. Because of the jet orientation, the non-thermal blazar emission is
Doppler beamed; its variability is unpredictable and occurs on time-scales from
less than one hour to years. The comprehension of the diverse mechanisms
producing the flux and spectral changes requires well-sampled multiband light
curves on long time periods. In particular, outbursts are the best test bench
to shed light on the underlying physics, especially when studied in a
multiwavelength context. The Vera C. Rubin Legacy Survey of Space and Time
(Rubin-LSST) will monitor the southern sky for ten years in six photometric
bands, offering a formidable tool to study blazar variability features in a
statistical way. The alert system will allow us to trigger follow-up
observations of outstanding events, especially at high (keV-to-GeV) and very
high (TeV) energies. We here examine the simulated Rubin-LSST survey strategies
with the aim of understanding which cadences are more suitable for the blazar
variability science. Our metrics include light curve and colour sampling. We
also investigate the problem of saturation, which will affect the brightest and
many flaring sources, and will have a detrimental impact on follow-up
observations.
