  Cross correlation analyses of high resolution spectroscopic data have
recently shown great success in directly detecting planetary signals and
enabling the characterization of their atmospheres. One such technique aims to
observe a system at multiple epochs and combine the measured planetary radial
velocities from each epoch into a measurement of the planetary Keplerian
orbital velocity $K_p$, constituting a direct detection of the planetary
signal. Recent work has shown that in few-epoch ($\sim$5) data sets, unintended
structure can arise at a high level, obscuring the planetary detection. In this
work, we look to simulations to examine whether there are ways to reduce this
structured noise in few-epoch data sets by careful planning of observations.
The choice of observation date allows observers to select the primary (stellar)
velocity - through a set systemic velocity and chosen barycentric velocity -
and the planetary orbital phase, and so we focus on the effects of these two
parameters. We find that epochs taken when the primary velocity is near zero,
and the stellar lines remain relatively fixed to the telluric rest-frame,
greatly reduce the level of structured noise and allow for much stronger
planetary detections, on average more than twice the significance of detections
made with epochs using randomly selected primary velocities. Following these
results, we recommend that observers looking to build up high-resolution
multi-epoch data sets target nights when their system has a near-zero primary
velocity.
