Yes indeed. It does seem irrational to go from a timetable that's easy for regular commuters to remember, to such a quirky (or irksome) random timetable.
Unfortunately for those who use local train services from Berkswell, our Government recently deemed higher-frequency inter-city services from Birmingham to London more important, and dictated terms about how things should work.
To accomodate higher frequency services into London, the timing and frequency of local services had to be butchered to fit everything in. As a result, the gaps between services from Berkswell station are now all over the place. There's still as many services, but we're now required to plan more carefully before travelling.
The problem we're experiencing now has been caused by economical and historical constraints. From an economical stand-point, the Government deemed high frequency services to London more important than local services on a rail network that's busting at the seams with trains. And historically speaking this sorry state of affairs has come about as a result of massive under investment in the railways over a period spanning decades. The strongly advertised and massive recent investment in rail infrastructure has in reality been akin to slapping a sticking plaster on a long unattended, and gangrenous wound.
And adding further history into the mix, this problem is further compounded by the fact the Government ordered the railways (during the 80's and early 90's) to sell large swathes of land that could have been used to lay extra tracks. The railways are now hemmed in so badly by privately owned land there's few places where extra tracks could be laid to relieve capacity problems and provide customers with a decent local train service.
It's such a tale of woe I think I'm going to cry now. Sniff. Boo-hoo. Someone get me a tissue.