I'm well aware of what a spring tide is, Aust Wharf and Parkgate on the Dee Estuary give some superb spectacles when they occur. Shellness on Sheppey to some extent too.
And their cause is when the sun, moon and earth align twice every month, increasing the gravitational force on the seas.
But we only get really high tides as a result a few times a year. Partly due to weather conditions: a high pressure and wind blowing the sea off the land will see a significant reduction in the high tide level, and vice versa.
What I am not totally clear about is, even taking account of the weather as above, is why more of the twice a month spring tides don't see very high tide levels.