Source : MGMAT SC Guide Page 129 . 4th Edition.

MGMAT says : I walk faster than Brian.
Meaning : I walk faster than Brian [walks].

MGMAT says : I walk as fast now as when I was younger.
Meaning : I walk as fast now as when I was younger.

As far as I know, we can omit words only if they are exactly the same in the second part of the sentence.

For ex: I corrected some mistakes, and he others.
Meaning : I corrected some mistakes, and he [corrected] others.

My Take 1 : I walk faster than Brian does.
My Take 2 : I walk as fast now as I did when I was younger.

Somebody please explain whether I am right or wrong.