Rolling in BJJ is weird. For the entire round you maintain a baseline activity level(like a jog) and then have intermittent bursts of speed and explosive movement(sprinting). Imagine yourself jogging for five minutes and then having someone yell at you to sprint, but you don’t know how long you have to sprint or how many times this will happen. That’s sort of what it’s like, but you’re also trying to move someone around while they move you. What then becomes important is the ability to set a pace you’re comfortable with and the energy to maintain it. One of the ways you can work on this lies within the 15 minutes of death. Speed is not the goal of the 15 minutes of death, it’s about consistency. I would rather you go at a slow even pace for the whole minute then burnout in the first 15 seconds and struggle through the next 45. It’s the same with rolling, you have 40 seconds of full go at most before you need 2 minutes to recover, in a 5 minute round, you’d get a minute twenty seconds of time spent not resting. The other part of this is you have to enforce your pace into matches and rolls. It doesn’t need to be a fast pace, but you should constantly be moving. If your pace is to stop and hold, you are no longer creating any dilemmas and the opposition is in control. Long story short find a pace that you can maintain for the duration of a round, and constantly work to improve your technique and cardio so that you can adjust to changing tempos should the need arise.