I read somewhere that since the earliest days of baseball pitchers, on average, through on average 100 pitches per start. Seems that pitchers would mix up very long and very short starts, and end up at 100 pitches generally.
Today, I found at the Sabernomics website, actual data on pitch counts over the years from 1988 to 2009, which shows much the same thing. Pitchers used to throw many more pitches in a game back then than they ever do today, but they also sometimes threw far fewer. And on average, the results are pretty similar.
Of course, this is all the era of the five-man rotation, long after the days of pitchers throwing both games of a doubleheader. That’s when pitchers were men.