Ripley this is not the doctors forum he does not answer questions over here .You have to go to the doctors forums.
I'm just here because I couldn't figure out if you were serious with your question there. I will just comment that tolerance alone does not equal 'addiction'. Tolerance is a part of 'physical dependence', which happens with many non-addicting drugs-- including effexor or beta blockers. The term addiction is probably the same as what psychiatrists call 'substance dependence', which you can find criteria for by googling 'dsm criteria for benzodiazepine dependence' or for whatever substance you are concerned about.
As for the rest of your question, changing from one mg of Xanax per day to one every other day wouldn't probably cause a seizure-- unless the person took all 14 tabs of Xanax in the first three days and then stopped completely-- which is not at all uncommon.