The exit counts double because its speed shapes the straight. Open the steering, use the width and get on the throttle without ending up off the track.
The corner exit is the section between apex and straight, in which you open the steering, let the kart run wide and get on the throttle. The honest answer to "Where do I gain time?": often not at the braking point but at the exit, because the speed with which you leave the corner carries along the whole following straight.
That is exactly what the learning procedure targets that an analysis of 60 years of motorsport textbooks (car racing, so a transfer) describes: you change turn-in and apex and then observe the exit: how early and hard you could apply throttle, how tight your line still was, what speed you reached [1].
The exit also has its own gaze pattern. An experienced racing driver in the simulator looked at the corner exit before full throttle, at a spot that was almost the same lap after lap [2]. And the throttle itself you open, according to the textbook, "progressively", not as a slam [1].
The corner does not end at the apex. It ends when you can accelerate fully again.
Entry criteria (practice standard):
From the apex you take the steering angle back step by step. Your kart runs wide by itself. That is intended: the textbook procedure looks for a line on which you stay "just barely on the track" at the exit while accelerating as hard as possible [1].
Milestone: You open the steering evenly in five corners without having to re-steer at the exit.
In the simulator the expert looked at the corner exit before full throttle [2]. Take that on: your gaze looks for the exit already at the apex. Once it finds it, you open the throttle.
Milestone: You apply throttle only when you have seen the exit, and you recognise the moment on video.
Textbooks describe throttle application as "progressive": "once throttle is cracked open it is opened progressively" [1]. Do not yank, do not slam, but wind it on. This applies especially while the kart is still turned in.
Milestone: Your throttle trace on the data looks like a ramp, not a step.
The exit is where beginners often run off the track. The DMSB regulations punish leaving the track with all four wheels with lasting advantage with a 5-second time penalty [3]. And whoever leaves may only rejoin if nobody is endangered and must give back any advantage [3].
Milestone: You use the track width at the exit and keep the wheels on the track, even in the heat of racing.
Textbooks recommend watching for improvement at the corner exit, for example "RPM improvement at the track-out" [1]. In the kart you look at your lap time or speed at the end of the straight and compare variant by variant.
Milestone: You drive three laps with one line and three with another and name which was faster at the exit.
At the exit you accelerate and are close to other karts and the track limit. A US analysis of emergency departments shows: in karting, collision with another kart was the most common injury mechanism overall (29.6%), and 43.7% of those collisions involved the head [4]. For head-involving injuries, rollover was the most common mechanism [4].
This guide explains and motivates, it does not replace training with a coach on the track.
Practise the exit on one corner without opponents: drive it ten times and make only one change before each pass. A tip from training, not a karting study: set a visible target at the exit, for example a mark on the kerb, and check whether you reach it without correction.
According to the textbook progressively, as soon as the steering starts to open and you see the exit [1][2]. A specific point in metres cannot be generalised.
Because you take steering back and build speed. That is intended as long as you stay on the track. The textbook procedure looks for the point where you just barely stay on the track [1].
Under the DMSB regulations you may rejoin if nobody is endangered and must give back any advantage. Lasting advantage can be punished with 5 seconds [3].
As fast as the kart accepts it. Textbooks call that "smooth": progressive and decisive, not slow [1].
Yes. If your coach sees your head and your throttle movement, they quickly recognise whether gaze and throttle run together.
Brake, Roll, Accelerate: The Three Phases of a Corner