Guild Wars 2

so if I have e.g. 55% condition duration, and say runes of krait that gives bleeding an extra 45%, that makes bleeding 100% duration but every other condition just 55%?

Yes.

Then if you use koi cake for example (+40% cond duration if you are not alreading using) your other conditions will have +95% duration, but bleeding will still have 100% duration because of the duration cap.