For I = nrow_Start To nrow_Stop
    Do
        If Nrow_Frm1 = I Then Exit Do
        If Nrow_Frm2 = I Then Exit Do
        If Nrow_Frm3 = I Then Exit Do
        If Nrow_Frm4 = I Then Exit Do
    
        Cells(I, ncol_Period).FormulaR1C1 = formula
    Loop While False
Next I