Siri in particular will wait as long as a full second to “ding” letting you know she’s ready to process a command … often interrupting your attempt to give the command. Alexa will very often fail to hear me say “Alexa” despite the audio conditions being quite favorable.
Both Siri and Alexa will misunderstand what you asked for and be completely indifferent to your attempts to correct them unless you interrupt them correctly. Afaict Siri can’t be interrupted by voice alone and Alexa can only be interrupted by something starting with “Alexa”. Once you are already “in” an interaction session with either of these tools you should be able to simply say “no, not that” or “no, <correction>” and the assistant should stop talking immediately, instantly, and not continue to blather on with the previous wrong interpretation.
No matter how useful these tools are in the hands of a power user, Siri and Alexa give the impression of being morons largely because of unresponsiveness, not lack of capability.