I don't think its about batching, the production line as far as I know can build different Golfs sequentially - even building a Match and an R next to each other.
Its more to do with the stock levels and supplier supply of the components.
Remember VW won't be making themselves many of the parts and even the parts they do make also come off of factory production lines themselves - eg gearboxes or engines.
Its a complex process to create your car from all of these pieces, ready for them to be in bins alongside a moving production line.