Meh I'm not so sure, 20 seconds is always enough time to get full rage during a Bloodlust. I streamed it so just watched back, I was on 87 rage again within 3 seconds of the first CS dropping off and I spammed Executes throughout, I used another execute outside of CS and still hit 120 rage at 6 seconds before my 2nd CS came up... So there was no doubt I would have had 2 full rage CS phases.
It's also no doubt though that the boss would have died before the ring buff had ran its course though if we had delayed it as I wanted. I can highlight the end of the kill and you can see for yourself if you want, rage generation was plentiful you can see the moment I realised the ring was up and panic spammed Execute outside of CS.