A reasonable request amount?

[Lampan]

I made a userscript that fetches images from manga and displays it next to the manga title on the follow page.
When I ran it for the first time, I didnt add a wait and basically made a hundred requests in less than a second which got me banned for an hour.
So what's a reasonable time to wait inbetween each request to get the image? Right now I've got it a 3 seconds. If I'm not allowed to do this, then I'll stop using the userscript.

 

[Plykiya]

@Lampan As long as it doesn't exceed one request per second you're safe.