I believe there should be a standard period of leave for players in the NHL but it depends on the type of injury. If it's very minor like a sprain or something that only takes a few days to heal then there shouldn't be a standard. If it's a concussion or something a little more serious, each player that sustains that injury should have to sit out the standard number of days to insure their safety and for the league to maintain responsibility for the players' safety.
You can not base recovery time based on the type of injury or sport it is obtained in. As in the NHL and every other sport, the recovery time is based on the individual and the extent of the injury. Each person bounces back from a injury at different rates. Requiring NHL players to take certain numbers of days off based on a set time limit is not plausible.
Standard leave times are not a good idea. This is because every person's injuries are different. A sprained wrist does not require as much recovery time as a broken ankle. The league should continue as is with respect to every player's injuries -- on a case-by-case basis. This will result in less player absences too.
Unlike other sports there just aren't as many recognizable names. Fans need their star players to return from injury as soon as possible to keep interest in the game. Also, hockey is easily the most physical sport. Those guys play with cuts and bruises and broken bones all the time. If the medical staff for the team thinks they can play, they should play.