What's the smallest duration condition that will still deal damage?

By default, Poison, Burning, and Bleed effects last a set number of seconds, dealing damage each "Tick".

While Poisons and Burning can be extended by reapplying the buff, bleeds cannot. All three can, however, benefit from traits, runes, and sigils that increase the duration of a specific debuff.

For example, the 2-piece bonus for the Rune of the Balefire is 15% burn duration. If you then look at a skill that usually applies a 1 second burn, you'll notice the tooltip now lists it as lasting 1 1/4 seconds. (It rounds to the nearest quarter second increment).

My question is, does that extra 15% of one second actually increase the number of times the condition ticks and deals damage? Or do I need a full second for there to be an actual increase in damage / ticks?

So it turns out this is very easy to test on a Rifle Warrior, since their auto-attack causes a single bleed, and the default warrior loadout includes a bleed increase.

In short, conditions only deal damage for full seconds. 7 and 3/4 seconds will still only cause 7 ticks; you need that last 1/4 if you want 8 ticks.

So for bleeds, at least, you want to make sure that you're not wasting traits or runes on half-ticks or quarter-ticks. Either up your bonus duration, or find something else.

For Fire and Poison, it's a little different, because reapplying the condition extends the duration. In this case, the duration bonuses are a little better with fractional ticks... as long as you can routinely apply the condition. 5 1/2 sec burn + another 5 1/2 sec burn will give you 11 ticks, which means your bonus duration is not wasted, you just have to put in more effort to get a return on your investment, as it were.