Yes, welbutrin is a med that has to be up to the "therapeutic dose" to be effective. Just 150 mg is usually not enough but they often start you on it slowly.

I remember when i got off of welbutrin - i had finally cut contact with my family, so after a while - a year? More? It felt like welbutrin was sitting on my head! I was released from my family stress, so i didnt need the welbutrin to tie me down to earth anymore.