Why not equal length intake manifolds?

[Kendo]

I was looking at WRM Offenhauser after reading about that Aussie racer on another thread and saw some intake manifolds Offenhauser sells. One was a six cylinder, one carb unit. The outer cylinders were fed by much longer runners than the middle two. So why not equal lengths? Is the air speed not enough to warrant it? But what about turbos? Wouldn’t they push enough air to have it make a difference?