Definition in Human Design is about whether your fixed centres connect into one piece. Triple split means three pieces, two gaps — about one person in ten. Each block flows on its own, but connecting all three takes gates from outside, and the person who bridges the first gap may not bridge the second.
Mechanically that means you need more kinds of outside input than a simple split does. One person present completes one gap; you need to change setting and change company so that different gaps get bridged at different times — so your natural tempo on big matters is long, and you're most likely to go wrong when hurried.
Where you'll recognise it: thinking something through means doing a circuit of a few places, different people give you different clarities, and being forced to decide on the spot leads to regret. Running well, you're the most many-sided person around: with every block clear, you see one thing from several angles and integrate with few blind spots. Stuck, you get hurried — others think you're dragging, you start doubting yourself as indecisive, and you decide in haste. What you need isn't more decisiveness. It's enough settings. Give yourself the circuit, and the answer surfaces in the second or third place.
