Dan Newland offers up some ideas on outboard sheeting when reaching.
Here are some photos I happened to stumble into when I looked at PTSA racing pictures. The pictures illustrate why you need to go to outboard sheeting when reaching.
Modern high aspect, low clewed jibs/genoas work well going to weather but suffer on a reach. When you crack off your headsail on a reach what happens is you twist off the top of the sail reducing power while the clew continues to line up with the inboard track. if you switch the headsail lead to the outboard rails, the leech would be straighter, the top less twisted, and with more headsail working, you have more power.
These photos illustrate this point perfectly. Photo #1 shows the headsail cracked off for a reach. The top of the jib is luffing and not pulling much at all.
Note in Photo #1 that the mainsail isn’t twisted off like the jib. This is because the vang is on. Photo #2 shows better trim with both sails having matching twist, the leech of the main mirrors the leech of the headsail,