There were far less trains on the network back in steam days though, and the concept of a clock face timetable (the same trains running at the same minutes past each hour with the same stops) is relatively new.
As part of my last job before retirement, I had to find paths for diverted Avanti trains during engineering works. In some hours, when I needed to divert Euston to Liverpool trains via Warrington and Huyton no paths existed at all due to the high frequency of stopping and freight trains between Huyton and Edge Hill. I had to terminate some trains at Warrington and provide onward connecting buses.
I understand this situation has changed somewhat post COVID with Northern and TPE service frequencies being slashed to cut costs, because of traincrew shortages and perceived drops in customer numbers.