If your plants are lightweight enough to pick up, that should be a good indicator. When it's still as heavy as when you watered = doesn't need a drink yet. I do water most plants on a schedule, though I don't take time to water those that don't yet seem thirsty. About once a week while inside for winter, every 2-4 days while outside, depending on the weather.
The concern about "overwatering" is really about rotting roots. Few people have time to water plants that don't yet need more water, but worrying that it's not yet "ready" for more water to be added is unnecessarily stressful and mysterious. Unless plants are cacti or some of the succulent types, most house plants are from moist, tropical places and would prefer to not become too dry.
This concern over rotting roots/overwatering has also given rise to myths such as, "This plant likes to be rootbound." No plant likes to be rootbound. What they like is for their roots to NOT rot, which can happen so easily in a pot with dense soils, like ground dirt, or bagged mixes of predominantly tiny particles of peat. Having very little soil around the roots makes it difficult for even the most dedicated plant-overwaterers to rot the roots of their plants. This is not ideal, just a way of coping with inappropriate "ingredients" in a pot.
A more porous, chunky soil (like cactus/palm, if one is buying bagged) can have air in it even when it is moist. Roots need oxygen and moisture at the same time to function. When there are tiny particles of any kind in a pot, such as peat, sand, silt, clay, they filter into all of the tiny spaces in a pot, eliminating the air. "Overwatering" is the label and manifestation when roots have suffocated and/or rotted, combo of both. There is no one thing folks can put in to make soil better, but removing tiny particles of any type will definitely help. Over time, organic bits decompose into smaller bits, so even the "best" soil, if it has organic components, will need to be replaced when this happens. The speed at which this happens depends on many variables, but on average, about 1-3 years.
