How to check if EBS is fully utilized and cannot provide more throughput

Question

I am using EBS volume(gp3) with m6in.4xlarge EC2 instance.

I read that the maximum throughput gp3 volume can give is 1,000 MiB/s and I am able to achieve the same.

How can I be sure that this is the maximum throughput provided by this volume. I tried checking the "Time Spent Idle" for this volume, but it is sometimes idle even for 60% of the time.(It should not be idle if all the throughput of 1000MiB/s is getting used)

Also, if I try to check iostat of the node getting used, it shows the disk utilization as 50% only:

How to be sure that the disk is getting used at its maximum capacity?