Everyone, of course, wants trains to run on time, but things happen (and always have and always will) which cause delay. Sometimes that delay might have no repercussions, in which case no action need be taken. In other circumstances however doing nothing is the absolute worst option; As a Controller I sometimes arranged for late running trains to miss stops (in Scotland, not Merseyside) because if nothing was done the late train would just get later, would delay other services, and would eventually lead to part or full cancellations. Yes, it would be wonderful to have sufficient spare capacity to allow extended turnrounds, standby trains and Traincrew, etc, but that is not the situation we are in, and doubtfully ever will be. Control has to do what it can to minimise overall delay and therefore impact the least number of passengers.