Re-stringing a racket comes down to the player usually. The club and recreational player usually re strings the racket only once the string breaks. For the club and recreational player this seems to be fine because they happen to break a string only after several months and some even take years. Either way for the club and recreational player it is ideal to re string the racket at least once a month or once in two months if playing every day as this will definitely lead to drop in tension which would lead to loss of feel and major drop in control.The professional player who plays 5-6 sessions a week would ideally like to re-string the racket every week or every 10 days at the max. It is ideal to restring a racket before it breaks because this saves more time and makes sure you get the max out of your session without having to stop the session due to a broken string. The pro player would also like to restring all his racket before going to a tournament. This ensures that the player doesn’t have to worry about breaking strings mid match or being worried about when the string would break. He could then go after his shots freely and play with as much power and spin as desired.Also, the type of string would matter. If the player is using a polyester string he/she could go for a few weeks without much loss in tension and this means they would not have to restring that often. Polyester strings are also much more durable than the normal multi-filament or natural guts.The multi-filament strings lose tension easily and have very less durability and hence rackets would have to be strung more often.