I'm not a regular Hollyoaks watcher but I've seen some of the self harm storyline... To be honest I find it all very cringe-worthy - it never seems genuine. It's good that it's raising awareness of mental health issues, but the problem is it has to do it in that awful soap opera way. I tend to roll my eyes at a lot of it!
Maybe I'm just older and more critical than I used to be because I remember the storyline with Lisa Hunter's self harming back in the early 2000s and I thought that was quite good.
I think you might have hit the nail on the head when you say the storylines seem too rushed now and are not being done justice.