[Neil Jones]

To flip the question around which long running shows have had the MOST title sequences?

Blockbusters is up to seven versions across all the incarnations. Yes it hasn't run continuously all that time but we've had more stabs at it than most other countries.

Somebody rather handily made a YouTube video about it, which is nice:
www.youtube.com 

The obvious example though to your question has to be Countdown, which again somebody has put together on a YouTube video showing said title sequences, though probably descends into evolution at various points later in a look's life than revolution:
www.youtube.com