I usually leave them on 7-10 days. So here is a question. How long would you leave WPL011 European?
I've never used that particular strain, but if it's like most other English strains then I would guess it would be done fermenting in like 48 hours, so then I'd leave it for about a week just to be safe.
General guidance for any fermentation: Wait until all signs of fermentation have totally ceased -- e.g., no airlock activity, krausen has fallen, beer has begun to clear -- and then check gravity, wait at least 3-4 more days, check gravity again. If gravity stays the same after several days, you are safe to bottle or keg. If not, wait a few more days and repeat until it's done.