Intermediate proof allows the dough piece time to recover before final moulding.
When the dough piece has been rounded it:
is rubbery and very dense
contains very little gas
lacks extensibility and tears easily.
Therefore it will not mould satisfactorily.
Intermediate proof provides a recovery period so that the dough can become more flexible and pliable. After proving, the dough piece is usually larger in volume, the skin is firmer and the dough stretches easily.