Actually, Jellicoe managed to cross the German T twice; they just maneuvered out of that fix before decisive effect was achieved by the Brits.
Nelson's contribution to sailing warship battle was to "break" the conventional line-of-battle by refusing to form up that way. Line of battle was a single-attack axis formation which was virtually decided by who held the weather gauge. Nelson's particular brilliance was to form his squadrons into what looked to the enemy to be a line-of-battle, and thus fix the enemy as they sought to own the weather gauge. This allowed Nelson to maneuver his squadrons to cut through the enemy's line, then turn back upon them in the weather gauge, having raked the enemy column with broadsides down their least-protected axes.
So, it was not so much crossing a "t" as hacking a dash into a plus sign. Which was also tactically brilliant. Nelson's enemies at sea often relied upon a single supreme commander, who led in a high-value flagship from the van. Command and control ran, but signal, from the lead ships after to the lesser ships.
Nelson's use of squadrons in slashing attacks effectively decapitated the enemy formation, and negated any advantage they might have had in numbers or weight of guns. Further, the enemy had the confusion of having gone from the relative sailing simplicity of the weather gauge to suddenly needing to maneuver, and this requiring hands for sail-setting and trimming--whose job was made far more exciting for all the shot, grape, and musket balls flying about.