Boilers will normally cycle when all the radiators and pipe work reach the temperature of the boiler thermostat.
If the boiler starts cycling well before the hot water and radiators are up to temperature indicates a potential problem.
You normally aim for a differential of 11C across the boiler flow and return pipes when the system gets up to temperature.
Excessive cycling can be caused by poor system design i.e. oversized boilers,old gravity systems, pipe work not sized correctly, etc.
Sludging/blockages, and failing pumps can cause cycling on older heating systems
TonyR