Question
In erection of false work, for a rectangular panel inside a false work would it be braced all along two diagonals?

Answer
While a rectangular panel is focus to the eccentric load or the lateral load, it tends to distort into a parallelogram with one diagonal shortening and other elongating.

Supposedly, it is enough to brace along one of diagonals if one diagonal is only allowed to brace inside the rectangular panel, it must be not braced in diagonal in compression as under severe lateral loading diagonal might buckle leading to failure of structure.

But, in actual situation lateral loads could come from both sides of panel and therefore it should be there braced in both diagonals.