Praying is basically talking to God. What you are describing here is people who only talk to God to ask for things. Do these prayers get answered. I
would say 100% yes. Is the answer "yes" every time. Of course not.
This does bring up a good question. Why doesn't God give us everything we want? Well, let's cut out all of the stupid things that people ask for and
say that we only ask for good things. Why can't we have every good thing we ask for? The only answer I can come up with is that maybe some of the
good things we ask for aren't as good for us as we think they are. It's quite possible that we aren't as wise as we think we are.
I don't believe that there's anything wrong with asking for help with a test, or praying for healing, but you should do as much as you can yourself
first. Study for that exam, and see a doctor if you're sick. In every instance in the Bible, when God performed miracles, the recipient had to
perform some task first. The Red Sea didn't part until Moses held up his staff. Elisha didn't heal the Syrian officer Naaman of leprosy instantly,
he had to go bathe in the Jordan river first. (Yucky) These small task seemed insignificant in respect with the miracle that occurred, but they showed
the receivers willingness to do their part.
I think if you've done your part then it's fine to ask God for extra help. You may not get the answer you think you should, but you have at least
done as much as you can to wards achieving that goal. Praying for things is fine, just don't use it as a crutch or excuse to be lazy.