Julian Cope presents Head Heritage

Any thoughts on why some circles are made up of a random bunch of standing stones of all shapes and sizes, yet others are well matched with regard to both circumference and height? Then you get the not so perfectly round circle compared to the perfect one. Does this mean that the precision of the circumference is of little importance?
Is the diameter of the circle indicative of its 'use', or because many people use it at one time? Down here on Bodmin Moor the large circles are seen as being 'ceremonial', but is there any reason why the smaller ones couldn't have been used for the same purpose whether ceremonial or not?
Why do some have centre stones, others have off-centre stones and 'most' none at all?
Questions, questions....