Why is my soil drying up so extremly slow?

Probably too small of a plant in too large of a pot -OR- not enough perlite or similar in the soil for proper aeration, which also reduces water per volume and that would help a plant drink it down faster if starting at a smaller starting volume. you want about 50% perlite or similar amendment to perlite (50% in sphagnum peat moss too) in anything that is similar water holding capacity as a basic soil. With coco you need 33% perlite because the coco fibers hold less water per volume by comparison to most soil or sphagnum peat moss. A small plant in a large pot brings up a ton of potential risks and problems.. avoid it as best you can. Water sitting stagnant in a water tank or in some soil is still sitting and stagnating. You don't want your pot remaining wet for 7-8+ days, and preferably even shorter than that. 4-5 day is about how long it takes after a transplant relative to my timing. Bet some wait for an even bigger plant before transplanting. 4-5 isn't so bad, because i know the 2nd irrigation will be 3-4, and quickly reducing from that point on until i can do it daily. (soilless context) so, if it is a big pot, tiny plant, water a column of substrate all the way down - don't half ass it. Start with a diameter about as wide as your canopy. It'll spread out wider underneath. keep increasing diameter as the plant grows. This helps mitigate the problems, but is not perfect. still have potential of dry pockets adding solutes, drying out and adding more, which can pile up into a potential toxicicty. in soil, wait for top 1" to dry, then repeat. This is important for roots to grow downward and not upward. you do want the interior of the pot to remain wet longer.. this promotes a healthy root system. you get more superficial roots if you don't water all the way down to the bottom consistently - whether a smaller column or entire pot never choose the volume of water... it needs what it takes to get the whole thing saturate (or a column wet all the way down in context of tiny plant + large pot)