Yeah, that's why in my mind I prefer several (3-4) smaller heaters. I also have a basement sump that sucks the heat out of my system. If one fails on or off, no big deal. On a 200-300 gallon system, if one or 2 even, get stuck on, definitely needs fixing, but shouldn't cause a catastrophic failure.
But that also means you have to pay attention to your system. You don't want one broken heater to be doing all the heating
You should know if they're switching on and off.