I have to ask the question - why does it matter?
He has had a serious injury. Presumably, you have done what you can from a learning and understanding perspective and implemented any improvements you can. Does it make any difference to how you operate whether he is off for 2 weeks or 12?
https://safetyquo.com/2016/07/03/lost-time-injuries-breaking-the-cycle/

I expect that with the reference to the 'Business Leaders Forum Benchmarking...' that the question is due to external reporting requirements.
I think there really is only one "person" that can definitively answer the question and that is who you are providing the reports to, although I wouldn't be surprised if you don't get much of a clear answer as I have found that determination of LTI days to be one of the worst detailed parts of these sorts of reporting systems (and even worst when it comes to what to do about subcontractors!)


If I had to decide myself, my approach would be to set the LTI days to what has been detailed by the medical professional without consideration of when the project finishes or the subbie was due to leave site - reason being is the injured person will not be returning to work until "better" - so even if the subbie had a job lined up to move straight onto after yours, the injured worker wouldn't be starting on the new job, i.e. the injury on your project has taken that person out of the collective industry workforce for however long they are out of it for irrespective of your companies project timeframes.

However I would expect that there is a good chance that any company that is benchmarking themselves against others would very much not want to take the above approach... which would then just make me question why you are bothering to benchmark yourself at all - as your own results would not be meaningful, and worst still if you'd do it then logically you should trust any or the other results (as it should be expected that they are fudging the numbers too)... but that gets into Craig's response.

Its a system I don't agree with but I am stuck with it unfortunately.
Yes it is a reporting requirement issued to us by our two Boards.
Your responses have given me food for thought but in saying that I am not in a position to influence our Board

For me the bigger issue is why is he still off work and not on a light duty rehab. That hairline fracture in the neck had better be quite serious. I would have thought a max of about 50 consecutive days.