  The Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) will
detect an unprecedentedly large sample of actively accreting supermassive black
holes with typical accretion disk (AD) sizes of a few light days. This brings
us to face challenges in the reverberation mapping (RM) measurement of AD sizes
in active galactic nuclei (AGNs) using interband continuum delays. We examine
the effect of LSST cadence strategies on AD RM using our metric
AGNTimeLagMetric. It accounts for redshift, cadence, the magnitude limit, and
magnitude corrections for dust extinction. Running our metric on different LSST
cadence strategies, we produce an atlas of the performance estimations for LSST
photometric RM measurements. We provide an upper limit on the estimated number
of quasars for which the AD time lag can be computed within 0<z<7 using the
features of our metric. We forecast that the total counts of such objects will
increase as the mean sampling rate of the survey decreases. The AD time lag
measurements are expected for >1000 sources in each Deep Drilling field (DDF,
10 sq. deg) in any filter, with the redshift distribution of these sources
peaking at z~1. We find the LSST observation strategies with a good cadence (~
5 days) and a long cumulative season (~9 yr), as proposed for LSST DDF, are
favored for the AD size measurement. We create synthetic LSST light curves for
the most suitable DDF cadences and determine RM time lags to demonstrate the
impact of the best cadences based on the proposed metric.
