If by 'efficient' you mean 'most consistently profitable', then no, neither markets nor a 'flexible corporate environment' promote actual efficiency.

In that kind of environment - which is not too dissimilar to the one we're in - corporations simply hoard money to no great end, and markets crash unless they're propped up by public subsidies and hand-outs.

This distorts the wider economy and makes real efficiency less likely.

Of course if by 'efficient' you mean 'providing the greatest possible benefit to the greatest number of people' that would be a very unusual aim in orthodox economics.