In a few large stations (Milano C., Firenze SMN, Roma T. and Napoli C.) the train may reverse its direction, in which case it will arrive 9-10 minutes before departure time. At intermediate stations, the stopping time may be in the 30 seconds-3 minutes range. - When the train departs from its initial station, the current trend is bringing the train to its platform not earlier than 10-15 minutes before departure time.
An example. I live 10 minutes walking from Firenze SMN. If a train to Milan is due to leave at 1pm, I leave home at 12.30pm. Ten minutes for walking to the station, 10 minutes for passing the ticket control (it takes one minute) and looking for the platform (usually announced only three minutes before the train arrives, 10 minutes as in SMN the train it will arrive 9 minutes before departure time.