If you look for fast hands away from the body dogmatically then the handle will decelerate into the catch and you will miss water. Additionally you will come onto the slide too early and the boat will move less distance per stroke: on the slide the boat is meant to move underneath you, not you over it; if you prolong the time spent on the slide outside of its correct ratio then you will weigh the stern down for longer and deeper and check the boat significantly. I like to think that there's a correct time to place the blade at a quantifiable boat speed and rate, and if you try to delay that timing of blade placement it has the same effect as missing water, even if you've only prevented the boat from moving past you on the slide. This is what Drew Ginn talks about in the famous "Will it make the boat go faster" video.

In my opinion, the handle should have a constant speed or increase in speed as the recovery goes on, as this is the easiest way for the handle to have as little effect on the momentum of the rower/boat system as possible. Emphasising the acceleration of the handle away from the body is something of a noob trap, as the benefit of newton's third law on the boat's speed is much less as compared to the deceleration effect on the boatspeed of the rower's body mass decelerating into the catch it necessitates.

In reality handle speed is a superficial measurement which masks the importance of ratio on the recovery - that of how long the seat is still, and how long the seat slides. If one allows the boat to move past them on the recovery, the slide speed should be determined by the boat speed. Therefore the rate can only be properly regulated (outside of pressure on the drive) by controlling the amount of time the seat is still, before one allows the boat to move past the seat.

A great race example is between Drysdale and Berrest, (Berrest himself an Olympic and world medallist) in a heat of the Diamonds at Henley '16. The difference between ratio of seat and slide between the two and it's affect on boat speed can be observed. Note how long Drysdale keeps his seat still on the recovery compared to Berrest; I think this contributes greatly to his ease of movement and distance per stroke.