with just under 700 metres of runway remaining, this was increased to maximum brake pressure and maximum reverse thrust was selected
There is a real trap waiting where the pilot elects to use only idle reverse on touch-down for whatever reason. Idle reverse on the CFM 56 engine is around 22% N1 (same N1 as forward idle). In the case above, the speed was around 80 knots when the pilot realised he had a problem of his own making, including the astonishing act of cancelling spoilers while still at speed.
He then belatedly hauls in max reverse far too late to have any appreciable deceleration effect. Not only is the speed is by now too low for reverse to be effective, but the lengthy period of time it takes to spool up in reverse from 22% N1 to max reverse N1 (around 10-12 seconds) exacerbates the lack of effectiveness of reverse. All the time his max manual braking from 80 knots down would further cause rapid slowing up where the max reverse is practically useless. So the oft used rationale that you can always pull in full reverse as a last resort if floating or landing long on a wet runway, is a myth. Because of spool up times from idle it takes far too long to be effective.
Operators requiring their crews to use idle reverse as policy need to be aware that if an event happens (wet surface for example) where normal braking efficiency is suddenly reduced during the landing roll and too late the crew need to re-introduce full reverse from ground idle, it will probably be a waste of effort as the aircraft will be close to stopping whether on the hard surface or beyond it.