At the level of individual financial institutions, the growth of bank balance sheets was seen as reflecting increasing returns to scale and scope from combining a wide variety of financial services and providing them cross-border to internationally active clients. It is also possible that returns to scale in the largest banks stem from leveraging the superior skills of high-performing teams of bankers.
In fact, we could aspire to a period during which growth could be a bit above trend for a while, since spare capacity in the economy has increased a bit over the past eighteen months or so. Monetary policy has been playing its part to support demand.