Make space for towels to dry
A hook can hold a towel, but a spread-out towel has a better chance of drying between uses.

Give the wet cloth some space
Look at a towel half an hour after it has been hung up. If most of it is gathered into a thick bunch, the hook is serving as storage rather than useful drying space. Where the room allows it, open the towel over a rail so the layers are not pressed together.
Two towels on one short rail may look tidy but keep each other damp. Separate them or use an additional suitable hanging point. Check any rail or hook's fixing and load instructions before adding more weight. A wet bath sheet is a different load from the dry hand towel used in a product photograph.
Keep the towel clear of a wall that remains wet after bathing. A corner behind the door may be convenient, yet receive little moving air. The best position is one people can actually use without brushing the cloth against the floor or shower spray.
Fit the routine to the room
In humid weather, plan a second place to finish drying towels if the bathroom stays damp. A stable drying rack in a ventilated suitable space can help, provided it does not block a passage. Keep electrical equipment and trailing cords away from wet areas; do not drape fabric over a heater to speed the job up.
Rotate towels when needed rather than putting a fresh one on top of a damp one. A small household may manage this with very little extra linen. A busy shared bathroom needs clearly assigned spaces so one towel is not repeatedly covered by another.
If a towel has developed an unpleasant smell, simply spraying fragrance on it does not replace washing and drying. Launder it according to its label and check whether the hanging arrangement caused the problem. Use the opportunity to inspect the rail behind it and clean that surface as appropriate.
Store only the dry ones
Before folding a washed towel, feel the thick hems and corners as well as the centre. Those parts may retain moisture when the main cloth seems ready. Give them more time if necessary.
Keep the clean stack loose enough to remove a towel without disturbing everything. Do not use the linen cupboard as the final drying stage. If the same towels repeatedly struggle to dry despite a better arrangement, a smaller size or lighter construction may suit that bathroom more comfortably than adding more of the existing type.