I've noticed that, if you use Fel Rush twice, Momentum is different than how it was in Legion. Before, in Legion, if you used Momentum again while the buff window was up, it reset to 6 seconds. It appears that now, instead of starting a new 6 sec window, it actually extends your current buff window to ~11 seconds (cast time/GCD). Is there any benefit to using FR twice in a row, and then dumping fury?