I love IEMs , They are almost my favourite type of phone, isolation, light weight, and an intimate sound.
I don't fuss over db , but keep the levels at my own volume 'sweetspot' above or below this I don't enjoy the sound as much.
Recordings and music tend to have their own 'sweetspots' but these have to fall into my own.
If that makes any sense!
But then I am not an endurance listener , I am amazed at the hours some people listen for!
I guess it depends on personal circumstance , I sometimes have the radio on at piffling low levels, but don't really class it as listening.
With my audio system I prefer an hour of glory over many hours of murmur.
People must look after their hearing for sure, but it will eventually degrade with age, So best to enjoy it when it's on top form whilst exercising caution to keep that way as long as possible.
IEMs are great here because when you turn the music off, your are wearing hearing protection!
And for those people who are completely lost as too what is a safe level and worry about getting db meters etc,you need to reacquaint yourself with your ears!!
Just as with learning to listen for subtle differences in equipment , learn to understand what your ears are telling you with spl levels.
Often people who eat lots of salt sugar , fried foods etc lose perspective on flavours, same with hearing.
If you listen to audio electronics al day long , that ain't hearing!
Stop listening for a while,get used to quiet environments with soft sounds , use ear plugs whatever it takes to re-adjust.