In the rectifier circuit; the use of diodes in series can increase the back pressure withstand value (usually the sum of the back pressure of all diodes, but it is best to use diodes of the same specification).
In the voltage stabilization circuit; the series connection of the diode is equal to the sum of the voltage stabilization value of the diode. The use of diodes in parallel is theoretically the sum of rated currents, but considering that it is impossible to be absolutely symmetrical, they can only be used below 80% of the total.

TVS transient suppressor diodes work in the same way as regulator diodes, but there are structural differences.The biggest difference is that the PN junction area composed of the general regulator diode is very small, it can withstand the reverse current is small.