My wife and myself gave regularly years ago may have got to 18 pints between us but my wife stopped when they stopped the numbing jab and struggled with it...I kinda fell out the habit soon after, i found it harder and more uncomfortable due to no local jab.
Whether it's psychological I don't know..
I used to donate for many years
I was never that bothered by the jab
but my friend found it painful even without the numbing jab first - she really didn;t like it
but carried on because she had needed atransfusion herself a couple of time and her parents had as well
so she did it anyway
but there is a limit and that is down to the individual - I know she stopped after a while because it got too much
personally I stopped when it became more difficult where I worked
I did try to start again but could never get an appointment locally - which is weird
and then when I did they turned me away due to iron level (which started a whole who saga that is still going on)
worth doing and I would if I still could