Nice pace on my YZF600r though it prefers to sing around 6 to 7 grand. Still 5 grand & I am over the speed limits here in Cdn. So I would not call that as high revs for most riding & often I will be in 5th or 4th to let the revs climb up a bit. The bikes like to be able to sing a bit in the higher revs.
Honest to gosh a good sportbike power-plant is almost human. Look at the red line, look at the 'on pipe' revs & latter is where the engines seem to be happy.
Look . . . the people you are after are the people you depend on. We cook your meals, we haul your trash, we connect your calls, we drive your ambulances, we guard you while you sleep. Do not fu|< with us.
I think you're asking if you'll hurt the bike at that RPM and the answer is NO NO NO. That bike could run around all day at 12k and not hurt a thing. You'd make far more noise and burn unnecessary gas but you won't hurt the bike.
The other part of your question I think is what RPM is a good place to ride. From a safety perspective I'd say not to ride in too low an RPM if you're in traffic and may need to accelerate to avoid some bozzo who's trying to hurt you. Thus, ride at an RPM that gives you decent acceleration. I'd guess that CBR moves plenty quick at 6k and probably fine at 5k. Assess how threatened you feel and if it's getting tense downshift to get higher RPM's. If there's no one around for miles then you can run lower RPM's to suite your mood if you're just cruising then 3k may be fine. From a mechanical standpoint you can ride as low an rpm as the bike allows. If it runs smoothly without sounding stressed don't worry. Maybe as low as 1200 RPM with light throttle or 2k with heavier throttle.
I quoted you the revs of my 600 that has a better mid-range power then your bike & red-line is only 13thou so what I feed you was pretty easy to work out with your 600.
OFTEN on the hwy I am in 5th gear when doing 60 to 75mph or even 4th if I decided I want to get by this string of 4 to 6 vehicles all doing around 60mph.
Was doing that to-day out on the hwy & often letting the bike hum along at 85 to 100+mph (max limits of 50, 55, to 60mph) YET having to travel through the city of Penticton I was never higher then 4th gear & more often in 3rd as it was Saturday so traffic was often at a crawl so then 1st & 2nd so often.