Beginners should definitely rely on judging by the weight of the container, or a moisture meter... although one must test several areas in the containers to get an accurate idea of total moisture.
It is important to the growth of a healthly and strong root system to let plants dry out quite a bit between waterings. It can take several years to understand your plants and their needs enough to feel safe drying containers longer than a few days. However, with gained knowledge and a moisture meter you can easily push your girls to their limits without fear of stress.
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