Rope trick in 5e says:
You touch a length of rope that is up to 60 feet long. One end of the rope then rises into the air until the whole rope hangs perpendicular to the ground. At the upper end of the rope, an invisible entrance opens to an extradimensional space that lasts until the spell ends.
The extradimensional space can be reached by climbing to the top of the rope.
Movement is halved when climbing. Theoretically a character with movement of 30 feet could climb down and up a 7 foot rope during a turn by expending 28 feet of movement (7ft × 2 each way)
Given these details, if a character casts Rope Trick with a 7 foot rope and climbs into the space... then on subsequent rounds could the character expend 14 feet of movement to climb down the rope, perform an action, then expend 14 feet of movement to climb up the rope and back into the extra-dimensional space?
Taking this further... could the rope be just 3 feet in height and a wizard duck into and out of the extradimensional space each round?
Of course, the risk at this low height is that enemies might climb into the space as well. A dragon could put its head through the hole and breathe. Other mayhem is possible. But, it may also give a character in dire condition a brief respite against ranged attacks or spells.