I was watching this video of Roger Federer(below 1:04 min). Someone ask how many racquets does he used a year he said 50 to 60 with 600 to 800 restrings per year. That would put his number of restrings per racquet around 13 before he replaces it. How many restrings do you guys go before you notice any changes on your racquet? Does this mean after only a dozen or so restrings your racquet is performing below spec?