It is my belief that they're pretty lenient on that. Take the 2009 Twins as an example. Three pitchers -- Scott Baker, Nick Blackburn and Carl Pavano -- have the asterisk. But I sincerely doubt that either Baker or Blackburn ever started on three days rest in their entire careers.
Starting on short rest has long been a staple of elimination series, and I don't want to take it out of the picture here. But I also don't want to see a team make an extended run with just three starters of truly limited durability. At the same time, I look at the 1969 Dodgers and see a team that really could go a month plus of such series with just three starters.
So, my rule:
Any pitcher with the asterisk is permitted to start on three days rest, as described in the post on the schedule. BUT a pitcher who does so loses an inning on his point-of-weakness rating, and continues to lose an inning with each consecutive short-rest start.
The exception, through the round of eight: Any pitcher who
- pitched at least 300 innings or
- made at least 40 starts
in the given season may start on short rest without penalty.
Strictly speaking, 12 pitchers meet that criteria:
Claude Osteen, Bill Singer and Don Sutton, 1969 Dodgers
Ferguson Jenkins and Bill Hands, 1969 Cubs
Larry Dierker, 1969 Astros
Bob Gibson, 1969 Cardinals
Denny McLain, 1969 Tigers
Dave McNally, 1969 Orioles
Gaylord Perry, 1969 Giants
Mel Stottlemyre, 1969 Yankees
Charlie Hough, 1987 Rangers
Juan Marichal of the 1969 Giants misses by one start or one third of an inning. I will round him up; he's a durable Hall of Famer, not the kind of pitcher this rule was intended to discourage from starting three times in a long series.
(Interesting how sharply workloads declined from 1969 to 1987. Nobody in 2009 comes close to qualifying on either count.)
In the round of four, the standards will be relaxed to 35 starts or 250 innings, with the proviso that penalties already earned remain.
In the championship round, any asterisked pitcher may work on short rest without further penalty. Existing penalties remain.
The 1969 Dodgers will definitely use a three-man rotation. Between them, Osteen, Singer and Sutton started 122 of the Dodgers' 162 games and pitched 930 of their 1,457 innings. Could they stand up to a month of three-man rotation in series play? I don't see why not. They worked that kind of schedule for the full season.