RELATED IDEAS
Reduce Email Delivery Time (to a consistent 30 seconds to a minute delay after last activity)
As a user, my expectation is that I should receive an email notification in a minute or less, otherwise I assume that the email functionality is broken. Some Aha! emails come through almost instantly, while others take anywhere between 5 and 30 minutes. I understand the justification behind delaying emails until an action has been completed, but I can't imagine why it should be delayed any more than 30 seconds to one minute after an action has been performed without future activity.
As you mentioned, we do currently have an email delay to ensure that the action has been completed (prior to sending an email). After getting ample feedback, we decided on 30 minutes as this seemed to be the right amount of time where we could be confident that the majority of use cases would be completed in this time frame (to avoid multiple emails getting sent out).
In situations where you would like Watchers to be immediately notified, we also have this functionality on features where you can immediately send an email to watchers.
At this time, we don't anticipate making changes in this area, so that we can limit the amount of "noise" which might get sent out.