Rusted coins not working properly?

[Spider]

As I understand it, rusted coins are supposed to last 5 minutes, yet every time I use one the increased luck goes away after killing 1-2 mobs. It's strange. I'll see the icon in my status, but then it disappears.

What am I doing wrong?

[General Malarky]

http://darksouls3.wiki.fextralife.com/Rusted+Coin

Rusted Coin Usage

When grinding for Items specifically, you always want to use a Rusted Coin or a Rusted Gold Coin.
Increase Item Discovery per 50 points.
Their status effect's duration is 65s.
No. Held limit: 10

[Facepalm]

5 minutes? no way, more like a minute.

[Spider]

Ok, it's because I was looking at a different Dark Souls wiki, and apparently it's wrong. Thanks for the help. <3