Talk:Status Effect/@comment-142.196.41.201-20151102190737/@comment-137.112.156.106-20151102211129

I believe all of them are except corrosive and maybe impact.

Heat/toxin make them take extra damage at a rate of 50% of the damage you hit them with per tick, with 7 ticks in 6 seconds for Heat or 9 ticks in 8 seconds for toxin, so longer is better.

Viral doesn't do damage, it locks them into half health for its duration, so longer is still better.

So there aren't any status effects that are made worse by duration AFAIK, thus no duration reduction mods (except Rapid Resilience, which reduces duration of stats inflicted on your warframe)