Trigger Delay is not behaving as described in it's current tooltip, i.e. "Executes output trigger after the given delay time from the most recent execution of the input trigger." Namely, it is outputting a trigger for every execution, not just the most recent one.
(While outputting a trigger for every execution is sometimes desirable, that's what the Trigger Pipe node is intended for. At the moment these two nodes behave exactly the same way, and they should not.)
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-183510 in the post.