Is the patern shown varied to account for local conditions, or a standard size fits all?
That is not a very clear question... The example shown was fixed after discussion with neighbours, and both they AND the airfield management really insist on respecting it. Extending the upwind/downwind are tolerated but the downwind must absolutely be flown as drawn, at all times. Even worse would be to overfly the Bokrijk open-air museum south-east of the field…
Similar or even more stringent examples at Grimbergen EBGB, or the ultralight field of Maillen EBML - active NIMBY communities everywhere, so it is in the field's interest to give them as little occasion for whining as possible. This is why almost all fields carefully fix their circuit, and one really needs to respect that.
BTW similar traditions at most small fields in Germany. France is looser, of course.