Lambda used to mean the smallest size feature that could be reliably realized in the design. At the same time you still needed margin to carry current and to resolve any imperfections.

So the smallest thing you could make might actually had a minimum requirement of 2Lambda.

I don’t do ASIC gate layout any more but I expect that when they say 7nm now or 5 or whatever they really mean that they can resolve a 7nm feature but you still need 2 or 4 lambda to actually make it work.