I have to re think this. Maybe jackdaw can help me out. Let's say I was closehauled with the traveler almost centered and only the twist that the sailmaker built into the sail and I was hit by a gust and to compensate and get the boat on it's feet I decided to drop the traveler and not touch the mainsheet. I'm trying to picture in my mind what would happen to the shape of the sail due to the mainsheet. Actually, since the mainsheet on my boat is attached to a car on the traveler I don't think it would have any effect but I'm not sure. With the curved track traveler I used to have it would have an effect because the traveler car is going downhill on the curve. Maybe the confusion is I'm not taking into account different traveler/mainsheet set ups. If the movement of the traveler caused pressure on the mainsheet it certainly would effect the shape of the sail.
Sorry I was out sailing last night and just am back at it. I think my post
https://forums.sailboatowners.com/i...rpowered-situation.193323/page-3#post-1483735
summed it up. Only the vang and the mainsheet actually ADJUST twist; they are the only controls that can adjust the distance between the head of the main and the clew. If one or both of them is fixed, then the traveler positions the mainsail's (with its set twist) angle of attack into the breeze.
When a puff hits, most often the best action is to change the AoA of the sailplan to match it, without changing twist. The two ways to do that are to 1) lower the traveler, or vang sheet and ease the main.
If the puff is too big or also comes as big lift, it is sometimes necessary to also at twist (dumping the top) to keep the boat on its feet.
All boats have differing setups and levels of adjustablility. The key is to listen and read and learn, but also to apply the theory presented into actionable steps on your own boat based on its capabilities.