that's funny, I was just recently watching several Borg matches & took my own stats as far as how often he S&Ved(don't have them with me, but will get back to you with them later)
1973 QF vs Roger Taylor(a 5 set loss) 17 year old Borg S&Ved on virtually every first & second serve.
1976 Final vs Nastase-Borg S&Ved on every first serve, very few 2nds
1977 Final vs Connors-Borg mixed it up, not S&V on firsts as much as vs Nastase(guess that Connors return made him wary), never came in on a 2nd
1979 Final vs Tanner-just watched the 5th set, was an interesting pattern. Borg didn't S&V on any 2nd serves, but when he came in on firsts he won almost every point. a few games he didn't S&V at all & those were the toughest games to hold(maybe he was nervous, so he decided to stay back, which almost cost him the match, since Tanner was attacking relentlessly)