In reply to jollygreengiant1:
Guide book will give pitch length for a specific route, classic Diffs will often have option of short pitches as used in the first ascent but today most people will run pitches together where possible
(that means it needs to be a pretty straight line, and you have to extend runner's appropriately, can be easier said than done)
50m rope is what you will need generally
You can get a good idea about route from 'public logbook tab'
Giant's Crawl (Summer) (D)