I agree to a point, but doing problems without understanding what is going on is a waste of time.
For orgo, there are some key concepts that if you don't have your are screwed.
They are:
Nucleophilicity/Electrophilicity
Acid base chemistry (you need to memorize about 10 pKa's)
Resonance (this is a big one)
Reactive intermediate stablization
Once you understand these concepts, start drawing mechanisms for 5 the five basic reactions. (Free radical halogenation, SN1, SN2, E1,E2)
Apply the aforementioned principles to each step of the mechanisms and this will give you a great foundation. Look and think about what happens at each step.
Reactions of alcohols, alkynes, and alkenes are so much easier when you understand these concepts. You will have to memorize less than you would if you just practiced through "repitition."
You wouldn't believe how many kids I've tutored who can't draw a resonance structure. Do not be afraid or think you are wasting your time if you are in orgo 2 and you have to go back and relearn these key concepts. If you do this correctly, you'll save so much memorization in the long run. Electron drawing and donating groups can mostly be explained by resonance, as well as reactions with benzene's
Nothing tests your knowledge of reactions better than synthesis problems. Do as many as you can, then make up your own molecules and try to synthesize them. After you finish the amine chapter, a great way to practice synthesizing is to find structures for drugs and try to synth them. Look up structures on Wikipedia. It kinda makes it fun.
For NMR and IR, learn the key principles that make up each spectra. Look up the structure of molecules and draw what you think their spectra looks like. Check your spectra against the real spectra here:
http://riodb01.ibase.aist.go.jp/sdbs/cgi-bin/direct_frame_top.cgi
See if your spectra matches the real one and think about errors that you made. Do this "repetetivly."
In other words, make repitition count. If you think more, you'll have to practice less.
Good Luck
