Christmas cactus is an epiphytic jungle plant, like orchids, and not a true cactus. Drying out is not something they would experience naturally, but when in a pot of potting soil, which has very little air in it, drying out is a method used to avoid rotting the roots.
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.
The conditions you've described sound fine for temp and light, so it may need a bit of fertilizer to get it blooming.
