Rather than following a set schedule (such as twice a week), we recommend you monitor the water needs of landscape plants by feeling the soil moisture content directly. Using a finger or a wooden probe (so it's easy to see wetness on the wood), check the soil around five inches deep (excluding any mulch) and if it feels fairly dry, water the root zone of nearby plants thoroughly. If it feels moist to the touch instead, you can forego watering a bit longer, because consistently-soggy soil can suffocate roots. Watering on a schedule instead risks over- or under-watering since the current soil moisture level isn't being taken into account; precipitation is also difficult to go by since not all rain events soak in well or to the same degree. This page provides more information about watering trees and shrubs (though it applies to perennials as well): https://extension.umd.edu/resource/watering-trees-and-shrubs

Irrigation needs can vary by plant type too, since some are quite tolerant of drying out (and sensitive to excessive moisture) while others are the opposite (need to stay moist or intolerant of drought). For example, junipers need excellent drainage to thrive and tolerate brief droughts well; bigleaf hydrangeas, on the other hand, prefer to stay evenly moist. Japanese maple falls in the middle - moist but well-drained soil suits them best, so they neither want to dry out too much nor do they tolerate prolonged soil sogginess. Make sure any roof downspout outlets are not flooding a plant's root zone that won't tolerate wet conditions.

Air temperatures are less important than soil temperature, which lags behind air temperature since soil is much more insulating and changes temperature more gradually. Once the soil freezes (the couple of inches at the surface, anyway) you can cease monitoring for watering needs until we have a prolonged thaw with no rain/snow. Deciduous plants can be more forgiving of getting a bit too dry over the winter than an evergreen plant would, since evergreens continue to lose moisture through their leaves. Even though plants are indeed dormant above-ground now, their roots can continue to slowly grow in cool soil beneath the freeze line. Plus, staying hydrated helps plants avoid above-ground freeze damage. Cold temperatures will slow water loss, though wind can counter-act some of that and still dry plants out (especially evergreens).

Come spring and the return of mild weather, resume checking plants for watering needs. Given that the soil will remain cool for some time into the season, watering frequency will likely stay low for awhile. Since your plantings are new, monitoring them for watering needs their first full year or two in the ground will be key to minimizing stress while they establish and promoting the best root growth, which will boost their drought resiliency in the future.

Miri