Originally Posted by
Endus
The "caps" aren't points at which you cannot stack more Haste, they're points at which your current Haste has "maxxed out" its potential benefit for a given spell, and additional Haste will not benefit that spell any further. For instance, once you get Lava Burst to a 1s cast time, additional Haste can't reduce the effective cast time, since you're still limited by the 1s GCD.
You can (and will) continue to stack Haste on in addition to those caps, you just gain less benefit out of it. Even past the 100% "hard cap", you're still getting additional Flame Shock ticks from extra Haste.