Exactly, because updating the visuals required running the whole pathfinding calculation on each step of the move which made the whole action stutter. Only updating the grid visuals after the action has completed eliminates the issue.
At the end of my current lecture (where the jump/drop animations for moving between floors were added) he mentions there being an issue with adding too many floors and later on he will give some improvements… Since I made it configurable, if I wanted dynamic updates back all I need would be setting a flag in the inspector