This question already has an answer here:
Allow more than 1 comment upvote in 5 seconds Summary of that thread: "Can we change the 5 second limit on up votes?" Status: "Declined." My interpretation of the reason: An altered time limit might lead to more noise in the signal, the very thing the mechanism is designed to avoid.
My take is this:
The problem is not the time limit, the problem is the failure message behavior. I believe the "you can't upvote on a comment again so soon" message's BEHAVIOR is complete overkill, though I understand the necessity for the underlying time limit mechanism.
Problems with the current error:
- Brings up a popup.
- Displays the most visually noisy red error I have yet seen on the site, total overkill.
- Remains open until you manually click to close it.
- Provides no indication of when the functionality will actually be available again.
All just to tell you that you're being a bit too eager in your non-value-changing upvoting.
So I argue that the problem isn't the mechanism, it's the presentation, and I think that we can propose something better and much less annoying.
What alternatives can we come up with?