I was actually promoting a stack as that would make things easier, but it&#x27;s still tacked on a solution that isn&#x27;t as good.<p>A well designed FSM doesn&#x27;t necessarily mean an easily read FSM.<p>I always try to draw states and transitions on paper, and I end up making a mess. That could be a flaw on my side. But I won&#x27;t be making the same mess with BT.<p>I don&#x27;t see how a FSM could avoid having transitions back and forth.<p><pre><code>  * Elevator is on level 3
  * A person in the elevator wants to go to level 4
  * A person waiting for down on level 5
  * A person in the elevator wants to go to level 2
  * A person waiting for down on level 2
</code></pre>
FSM would need to track current floor and direction.
Would need guards&#x2F;predicates on transitions for inputs
Could just be me, but I wouldn&#x27;t be able to draw a pretty picture with those.