Sweep up and in to light up the upper chest.
Drive the arc up and in. Keep that elbow bend fixed the whole rep.
Setting the pulleys low and sweeping the handles up to chin height drives the arc along the upper chest fibres, the low-to-high line that flat pressing never gives you. Cables keep tension on the pecs through the entire sweep, including the top squeeze where free weights go quiet, while your front delts assist the upward path. It has earned its slot as the upper-chest finisher on pressing days.
Low pulleys sweep upward and bias the upper chest, high pulleys sweep down and bias the lower chest. They are not interchangeable, they are two halves of a pair, so pick based on which region needs the work, or rotate them.
Around chin height, together or slightly crossed, with that soft elbow bend unchanged. Finishing too low means you have turned it into a front raise for your delts, too wide and you never reach the squeeze that makes flys worth doing.
Lighter than your pride wants. Flys put long levers on the shoulder, so the stimulus comes from a controlled stretch and a hard one-second squeeze, not from slamming the stack. If the elbow bend changes mid-rep, move the pin down.
