modelling process

Attached is a screenshot of a workout that I don’t think anyone(world tour riders included) could finish : 5 hours @99.9% of threshold. However the system seems to think that the last hour a smidge under threshold is no big deal as shown by the difficulty line that has basically reach its asymptote.

I assume you guys are aware of this but I wonder how the model explains this and why has it been modeled this way. Is it because adding another dimension that would take into account the ride up to each point in time would make the modelling problem intractable? Asked another way, in the future can we expect a fitness signature that would be function of the current ride up until now? (which would remove the asymptotic behavior of the difficulty line in the chart attached).

thanks

Screenshot_2018-04-06_13-48-34

The workout designer only models efforts of less than an hour or so. Long-term fatigue is not currently part of the workout designer.