After using the strings for about 5 matches over the span of 2.5 months, these strings became extremely brittle and felt like the strings were splintering. I couldnt control the ball what-so-ever and it was a very inconsistent hit. I do use a lot of topsin with my shots. I have a Babolat pure drive plus racquet (100 sq in). Is this normal for these strings? I had the tension set at 60. Here is the link to the strings I was using. http://www.tennis-warehouse.com/descpageACPRINCE-PT17.html There was a guy giving tennis lessons when I was playing about a week ago, he said he has been coaching for 15 years, and I asked him how often I should change my strings, and he said once a year because I am a recreational player and I dont play too often. Sound right? Thanks for any feedback.