Let me write here a few line to clarify a frequent issue: "How long does a Tesi last?" Although apparently very simple, this is a very difficult question since the real answer "It depends on how much effort you put on it!" will probably sound unsatisfactory to the most of you. So, please let me rephrase your question into "How long does it take to get some innovative result?". Yes, because this is what qualifies a thesis as a Tesi and not as a Tesina: innovative results! Unfortunaly, innovative results require effort, time, trial & error, and, sometimes, luck (especialy when if you find them earlier then expected) so it is almost impossible to say wheather this will require 6 months or 18 months (in the first case luck has put the boost to your work in the second you have probably spent too much time in completing the exams you have left behind ... at least this is my >10 years experience). In my opinion, if the answer to "How long does a Tesi last?" is one of the main criteria to select a thesis, please consider turning at any time your thesis from Tesi to Tesina (to make its duration fully predictable) or cosinder it as a unique educational experience you will never repeate again (unless you enjoy it so much you want to make another).