Layer Break - Calc' Optimal or user?

[b4sket_c4se]

I have read a few tuts (old and new) on burning, in relation to XGD3.  Is it necessary to specify the layer break as 2133520.

 

Or should I just leave the settings as 'calculate optimal'?

[LIGHTNING UK!]

Leave it alone (on calculate optimal), that info is read from the .DVD file.