Hello Mickey,

a multilayer switch can reuse the same HSRP group number on different interfaces and this is recommended practice on less powerful devices.

on a router you need to used different group numbers on different subinterfaces.

To give you an idea some years ago we had big problems with 25 HSRP groups on GE subinterfaces on both C7500 and GSR 12000.

The trouble was that every group was consuming an entry on the NIC packet filter that decides what destination MAC addresses are of interest.

I recommend you to avoid to have all 200 groups active on the same device.

We had to make half groups active on the colocated device and to control the usage of MAC addresses.

Clearly you are not facing the same limitations but using only 20 groups (consider that 16 is the maximum on other multilayer switches) can be a safe choice.

So HSRP can be not so innocent and lightweight in some scenarios

Hope to help

Giuseppe