Pre-War and Post War RAF and RAAF training on Pilots Courses and indeed at aero clubs, it was drummed into pilots to never take your hand off the throttle(s) during take off and initial climb; no matter what type of aircraft, single or multi. That may have been because early aeroplanes like the Tiger Moth and the Dakota DC3 had dodgy friction nuts which could allow the throttles to slip back, unless the friction nut was set real tight.. Also, it was the rationale behind co-pilots being taught to back-up the throttles under the captain's hand just in case the fiction nut was poorly maintained.
Of course, If the captain slammed the throttles closed for an abort the co-pilot risk a multi fingers amputation if he failed to removed his hand in time. A one handed rotation or lift-off was made with no adverse handling problems. Nowadays, this advice has long since been superseded so that in airliners, the thinking is the hand is removed from the throttles at V1 and both hands used to pull back the control wheel. . Not on the Airbus series of course which has a computer game stick. . There are a myriad of reasons, lost in antiquity, offered for the two handed rotation policy, with most of the reasons being personal opinions. One theory being so the pilot is not tempted to abort the take off after passing V1. How superstitious is that?