Is partial response to drugs is the rule in adhd treatment than remission ? most rct show maximum 40% reduction after 6 or 8 weeks? is this true ?

Not in my experience: RCT data is difficult to look past, but I can say that working with many ADHD patients and regularly tracking outcome scores, I find that utilizing treatments often results in remission of symptoms (as well as remission of depressive/anxiety symptoms that are also monitored along side (phq-9, gad-7, asrs). Stimulant therapies for ADHD have some of the largest effect sizes as well.

Clinical reduction : of significant symptoms of Inattention &/or Hyperactivity/Impulsivity that have caused harmful dysfunction in 2 settings since before age 10 is achieved in 80-90% of child & adult patients if a stimulant can be titrated to an optimal dose without significant side effects. If not, adjunctive non-stimulant meds for ADHD can be added. Optimal daily management is multi-modal. See CHADD.org.