Time span until previously transferred player can be transferred again

If you set transfer approaches to 'strict', you are only able to approach players that have not been transferred for two subsequent transfer windows (Note: approaches are declined by telling you that the respective player had just joined the club, even after half a year/in the second transfer window). However, in reality, you don't have to wait an entire year until you are able to approach a previously transferred player. Instead, players are allowed to switch clubs once each transfer window.