It all depends upon cash: modular systems can be built incredibly quickly, but they cost the earth.
At one time we were world-leaders in prefab construction - theres actually a film somewhere of them building council high-rise flats in East London in the 1960s. They set some sort of record in the film.
What rockpile says if you look when they are doing work inside fitting the heat insulation they are uaing bog standard loft insulation between the walls were over here it would be foil coated kingspan. Also the New Citizen M hotel in Glasgow is all modular well the rooms are