Cylinder stats don't usually have accelerator resistors. It's acceptable - probably even desirable - to have several degress of hysteresis between the switch-off and switch-on points so that, once the tank is hot, the boiler stays off until it has cooled a fair bit.
Most mechanical room stats which I have come across *do* have accelerator resistors but maybe you had one which didn't. The stat would still work - but would have more than a desirable amount of hysteresis for space heating purposes.