Not a weird question! I want to preface by saying that the depth of cuts doesn't correlate with the severity of someone's mental state. People may have "scratches" and still be deeply depressed and suicidal. Self-harm is a coping mechanism, and the psyche behind "cutting" can differ from person-to-person. Some may "cope" with seeing a teeny bit of blood, but others may require deeper cuts and gushing blood. Those camps of people can have the same mental state and suicidality.

For him, I envisioned cuts with no standardized depth. When Jisung tends to an open cut (4th of July chapter), he uses "butterfly bandages," which (from experience) you'd use for cuts that bleed moderately and aren't super deep. In one chapter, I specified that the cuts are of variable depth. (Can't recall which one it is though, sorry!) When Jisung finds his "devices," they're all weapons of different sharpness, and by extension, would cause cuts of different physical severity.

It's hard to gauge his mental state because his perspective is passive in H2BH. What you get, as a reader, is heavily filtered through Jisung's thoughts and ideas. Even so, it's reasonable to assume that he isn't in a great place mentally. Acquired trauma, estrangement from his parents, and ongoing self-injury shed light on this. The next chapter will provide some more insight into his mental state!

I tried to explain without unintentionally spoiling what's drafted for future chapters. I hope this helps! :D