You MUST use some form of Protection!
The SB5 and Power Cab have built in over current sensing for basic self-protection that will continuously try to reset every half second until the unit is damaged. They do not have manual breakers that will trip or fuses that will blow. The default trip rating of an EB1 is 16ms. That is roughly 30 times faster than the Power Cab or SB5 overload trip time.
The reason you would add protection of some sort is that you don’t want the entire railroad to shut down if you have a short. You break it up into smaller pieces. All of our systems including the Power Cab will only try to protect itself and not your locos. Use the EB1 to divide up your layout and protect your trains! Think of this like the breaker panel in your house.