The max swing path that I can achieve is 30 deg with swinging the stick offline no matter the difficulty level. I done some extensive testing on all the settings and effects, so here it is.
First, the presets set the max amount of off axis for a 30 deg swing path. Hacker 6 deg, Am 12, Pro 18, TP 24. Now you can increase that by 15 deg with max draw/fade in the shot setup at all levels.
Next is snap assist, a better terminology for mouse and controller would be swing path assist. Though I can't really confirm there may be some forgiveness on the X axis. Mainly it changes the ratio between the controller swing path and the in game swing path. In the driving range the first set of numbers you see after after impact at the lower right is the controller path input readings. The post shot is the results of the difficulty setting multiplier. Max is a true 1:1 between controller and in game. Mod is a 1:2, where 5 deg nets 10 deg in game, Min 1:3, Off 1:4. So Off, a 7 deg swing path will net 28 deg, anything above will net you the 30 deg max. If you try to angle the controller more than 30 deg you will start to lose distance or not even be able to take a full swing.
Last the sweet spot settings, at first I didn't think this had any effect. Where this has an effect is in the over swing. Max setting has no effect with over swing, any of the other settings (Mod, Min, Off) have the same effect, they increase the snap ratio by 1. So playing Mod snap difficulty, 100 percent power and under is a 1:2 swing path ratio, and over 100 becomes a 1:3 ratio. Min dif 1:3/1:4, Off 1:4/1:4, as you can see 1:4 is the max ratio. Exception to the rule is Max snap where it's a 1&1/2 ratio for over swing (4 degrees nets 6).
The settings I'm playing with now are, TP preset for max 24 deg off axis, Max Snap for a true 1:1 ratio, and sweet spot Min for a bit of variation of ratio. Though I do like TP, Mod, Max as it does play like AM but with the max off axis. For a default preset I'll stay with AM as I enjoy working the ball with my swing, anything over a 1:2 ratio becomes too hard to do.
So the answer to your question, John, from what I have experienced 30 deg should be the Max.
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