A built-in coffee machine that runs a descaling cycle regularly tends to avoid the brewing-inconsistency and dispensing problems that show up when limescale is allowed to build up internally, particularly in harder-water markets. Most units will prompt for a descaling cycle on their own schedule, but running one manually between prompts is a reasonable habit in a hard-water home.
If a descaling cycle won’t complete, or a limescale warning doesn’t clear after a full cycle finishes, that points to buildup severe enough to need a technician’s attention rather than a repeat descaling attempt at home.