There is a number of issues in play here:

1. The length of time for the tissue structures to heal
2. The length of time for the neurological connections to function normally (in the case of things like reciprocal inhibition etc)
3. The time for functional movement return
4. The time for performance movement to return to that required by their sport etc

The player should always be tested functionally 'off the field' to check that they are able to perform what they need to 'on the field' before they are given the all clear. This might mean working them into fatigue to see what happens, not just after 5 mins, but after say 20-30mins of continuous performance.

There is no golden 'time frame'. But the tissue healing as others have mentioned is the starting point.