Both hands on flight controls after V1 - tradition, myth or technical fact.

[18-Wheeler]

On a Boeing that can't happen (in theory at least) as the autothrottle (on the 747 Classic anyway) only advances the throttle to the takeoff power setting then disengages the clutch so the servo won't move the thrust levers. The PNF checks this on the mode annunciator panel and calls "Thrust hold".
I'd assume that most other Boeings are the same.

[Tmbstory]

Systems

FullWings:

Thanks for the comments, In my day the Jets were mostly manual systems, so my comment was based on that fact. In the more modern systems if the thrust levers put the brakes on automatically that shows the importance of braking when on a "Stop".

Regards

Tmb