I'd say most suicides are rational and had years of suicidal thoughts behind them. I know that men and particular older men commit the most suicide, they take the time to weigh the pros and cons, research methods etc. before deciding to go.
The younger you get, the more emotional/situational a suicide gets in general and with that you get more impulsive attempts. I'd guess these suicides make up less than 25% of all total suicides, although they make up the bulk of Hollywood depictions.
I think those, who commit suicide impulsively, or swiftly are more likely to have had a better go at life, had they continued, obviously.
I agree with this as well. OP seems to just be completely guessing with his 90% number lol.
In my mind, the older the person is who commits suicide, the more likely it is that they have thought it through and are doing it because of their overall situation. Younger people are more likely to be impulsive and choose to attempt suicide over smaller things and less life issues.
For example, a younger person might choose to CTB because they broke up with their SO, got caught cheating on a test in university, got kicked out by their parents, etc. Basically, they are emotional and don't know what the future holds, so they choose to CTB.
An older person might choose to CTB because they have larger life problems. Maybe they got fired from their job and are now looking at homelessness. Or they have found out about a significant medical problem that will decrease their quality of life significantly in their remaining years, leading them to CTB.
Obviously, these aren't universally true at all, but this is just me talking in generalities.
Here is a graph showing suicide rates by age groups:
Personally, I assume people committing suicide in the 85+ group are doing it for less emotional reasons than those in the 15-24 group (on average), but that's just me.