Gabriel Burns of the Atlanta-Journal Constitution interviews Leo Mazzone about how the Braves prepared their pitchers in a short spring training for the 1995 season:

As he recalled, it wasn’t overly difficult preparing his pitchers on a shorter timetable.

“We started our spring in normal fashion,” Mazzone said. “We wanted to get them ready for five innings instead of seven, eight or nine. By their third or fourth start, they were pitching deeper in games. We didn’t change anything other than preparing them for five as opposed to seven. We kept a normal routine.”

AJC.com

Spring training is more about making money than preparation. It could be four weeks instead of six and prepare the players just as well.