Until last year the matches from the last 4 rounds started at the same time, 15:00 CET.
This year they made many changes. If you remember when we were joking with you Americans that you'll have to wake up early to watch Juve, because initially Juve were supposed to play the last 9 rounds at 15:00 CET and i think that not only the last 4, but the last 7-8 rounds were supposed to be played all at 15:00CET.
But later they changed the schedule again. First in one round they experimented with the Atalanta-Fiorentina match at 13:00 CET and with matches played at 17:00, 19:00 and 21:00 CET. Then they changed other things. Obviously, they also changed the schedule for the last 4 rounds.
I think they'll adopt the English model soon and matches from the same round will start at 3-4 different times of the day so more matches could be shown live.