The Wait node is what is called a “latent” node.
Latent nodes, only need one activation. As soon as they are activated (called) they will simply do their job at their own and once they are done, the “Done” output will be called. You don’t need to call latent nodes in a per-frame (update) basis.
Each call of a latent node will be queued. So for example in the following gif animation, you will notice that there is a number next to the Wait node title in brackers . Each time I hit the Fire1 button, the Wait node is queued to be called right after the previous (if any) Wait call is finished.
Let me know if this helps and clarifies how such nodes work.