FWIW here's my experience: mid 30s, New Zealand, wife read about ADHD due to young kids and recognised the adult symptoms in me. After some prodding I saw a specialist and was diagnosed.

I take daily ritalin - outside of the first few days (which were dramatic) I haven't had a life altering experience on the drugs, and tbh it doesn't change much whether or not I take it. However, having a diagnoses changes the way I approach things in life - it's helpful to know why my brain works the way it does, and how to work around it and with it. I don't think you need a formal diagnoses for this though.

It's extremely helpful to take a big dose just before a long meeting, to be fair. Where previously I'd struggle to even make it through, I can now be engaged.