I'm not very serious about nrl hunter, but I have shot a few matches with separate binos and rangefinder around my neck. I have shot fairly well and not timed out much. The first day of my first match was a shitshow. After that, I realized that I needed naked eye landmarks for every target just like shooting prs. Then timing out stopped being a problem. The last couple matches I have been shooting as a team. My partner shoots first and struggles with time management, so there have been several stages where I have had under 60 seconds to load the gun and shoot, some under 45 seconds. I think the few seconds saved with rangefinding binos would be beneficial, as I timed out squeezing the trigger on the last shot 4 times in one match and 5 times in another in those situations. In those instances, 10 seconds per match would have been good for 8-10 points. For a half second or so per stage of time that is a shitload of points.
You can get by with separate, especially if you are fast (I'm not). If you are extremely competitive you will likely encounter a scenario where you wished you had rangefinding binos.