yes

Only when you want to 心靜. if you have any stuff to take care of, you cannot afford 心靜, you do not want to 心靜, then 念心經 doesnot work instantly.

sample, if you lost a someone you love, you missed him/her so much that you cannot work or live a normal life, then 念心經 works.
sample, if your someone is very sick, you are running between hospitals, seeking medicines, preparing the next meal that is nutrients and tasty for him/her, then 念心經 doesnot work.

my personal experience. Hope help.