i'm 100% sure i've never seen a 5 week injury before :P
Before i hired my doc lvl 6 ( yes, i got a 6 for a pretty low salary and paid only 5k to get him :D was a hugh steal) i used to have doc lvls 1 or 2. Had a few long injuries their, but never longer than 4 weeks. Considering that i've never seen someone with 5 weeks injury, i think it's fair to believe that 4 is the max. If their was a 5 week injury, it should be more frequent and i've been playing BB for 15 seasons by now, so i should have come accros a 5 week injured player if that a player could be injured for 5 weeks... (then again, each season i learn new things, but a 5 week injury would defo qualify as very bad news...)