Quite a few simulationcraft scripts have target.time_to_die conditions, which are translated into target.TimeToDie() in Ovale. Simulationcraft does not simulate target switching; the target is always the raid boss, all adds are cleaved only. When the boss dies, combat ends, so these conditions are there to use up remaining cooldowns at the very end of the fight. In real fights, the target is occasionally an add, often shortlived; there's no point in using up cooldowns when it is about to die.

This is not too much of a problem for long cooldowns; anyone who knows enough about WoW to even install ovale would not use a 3-minute cooldown on an add that's only going to live for 10 seconds. This is a problem, for example, for Dire Frenzy ability for BM hunters; it has a 12 second cooldown with an occasional reset and is to be used as late as possible in the 8 second duration of the buff it applies, to have it up at 3 stacks for as long as possible. Even if I notice it and delay dire frenzy, I can't see the rotation because Ovale includes dire frenzy as the part of the main rotation.

My idea of fixing this would be removing all target.TimeToDie() conditions from all scripts; they are not to be used on adds anyway, and if the boss is about to die it is either going to die anyway, or the raid leader is yelling "give him all you got, all the cooldowns you have", and that's going to be more noticeable than any icon on Ovale.