HUH?
if you are taking off and one engine quits below vmcg or v1 you close the other throttle and now you are symmetric or pretty close to it.
I'm not really sure what you are getting at...and V1 is above Vmcg isn't it?
and in flight...use of asymmetric thrust is usually reserved for special problems like control problems
however, one can use asymmetric thrust in crosswind landings, allowing you a reserve of rudder...however again, you better know what you are doing if you are trying it for the first time with passengers aboard. certification is usually done with flight controls for x wind