Weeks At Number 1
I've never liked the way "Weeks at #1" is promoted. It lists Graf at 377; Navratilova at 332; Evert at 260 and Serena at 240. Obviously, the first computer rankings didn't come out until late 1975.
I've done some statistical work and come up with weekly rankings from 1969 until the first WTA rankings came out. I'm not claiming that these are perfect by any means. I simply gave points for events (somewhat subjective) and taken the top 12 point amounts from each player. I have weekly rankings for the top 20. (If anyone wants to see them, PM me and I'll send them. It's a big Excel file.) Also, the rankings are taken from a 12 month prior period. I know that a divisor was used when the rankings came out, but I don't think the archives I've used are complete enough not to miss some early rounds.
The main point I want to make is that using my system, Chris Evert comes out as #1 in April of 1974, as soon as enough Margaret Court points fall off from the prior year. In the first few weeks, BJK is fairly close, but after a few weeks, Evert opens a wide margin over King and Goolagong. Even with BJK holding the '74 USO and '75 Wimbledon, Evert's lead is still quite substantial. Evert played more and was more consistent.
And so, I propose that Evert would have had 81 additional weeks at #1 had the rankings come out earlier. Not enough to trump Graf, but enough to put her above Navratilova. Had the rankings been done differently, this figure might be lower (or higher - Court is #1 for several months while she is on maternity leave). Even allowing for discrepancies, I think Evert would probably be at least even with Martina in "Weeks at #1".