The busiest section is Moisenay junction to Pasilly junction (e.g. the end of the Interconnexion to the branch-off towards Dijon). I looked up Monday and direction away from Paris (Gare de Lyon/Massy/CDG). Between 15:50 and 20:00, I counted 46 trains (may have missed some).

Minimum headway was 5 minutes on the old units with old signalling, it's now 3 minutes with the TVM 430. But scheduled times usually alternate between 4 and 6 min, only sometimes down to the 3 min minimum. Yet this is not being generous with time: you need some buffer for lateness, and if the previous train has one more stop, then the next non-stop train must leave a longer buffer for the first train to accelerate back.

So with view to this, between these 46 trains from 15:50 and 20:00, I found just six empty slots (had they been used by trains from Gare de Lyon: 16:14, 16:34, 16:40, 19:34, 19:50, 19:54). And those slots will certainly be filled up once the TGV Rhin-Rhône and the line to Turin are built. Pretty close to saturation.

_{*Lunatic*, n.
One whose delusions are out of fashion.}