they achieved an edge in military stretegical planning which they kept.
Ok - so they knew what was going to happen, but they couldn't mind read, so they didn't know how to best respond to that which they knew because that would require the details they knew but had not yet known due to the lack of knowing while they knew but....
That's exactly the edge the Allies acquired in strategical planning: they knew they could not know where and how Napoleon will strike, but they definitely knew that by keeping coordination of independent armies larger than the single french one, they could avoid decisive defeat and concentrate later with overwhelming forces - nullifying Napoleon's tactical superiority.
Napoleon was master in manoeuvring one army with some detached forces. Allied learned the hard way how to coordinate multiple distinct armies with a common strategic objective.
Of course, this is easier to formulate today, but the practice was there : surprised, beaten, retreating english and prussian armies never lost contact with each other. Ensuring at least that Napoleon could not win a decisive victory in Belgium - which was strategically enough, giving the other allied armies on the move.