I hope you are talking about throw percentages and not expo. In a perfect world you would have your throw percentages on your highest rates at 130% for JR and I hear 140% on Futaba which is what you have here assuming you are talking about throw percentages

Then adjust the other rates to suit your taste and the plane.

On a new plane, since I fly JR, I will set my 3rd flight mode to 130% 20% expo on all control surfaces but ONLY if I am completely positive I will not bind the servo because the control surface is hitting somewhere or the servo arm simply cannot provide that much throw.

On the 2nd flight mode I'll set the throws to the book max for the plane with around 40% expo.

On the 1st flight mode I'll set the throws to somewhere around 50% for everything but the rudder and maybe the elevator depending on the plane and the size of the surface and I will use either 5 - 110 percent expo or none at all.

After all of that is setup I'll fly the plane and starting with low rates, start adjusting the settings as I see fit for me and my style of flying and slowly move through the flight modes until I get them all setup the way I want. This can take several tanks to a full gallon or two depending on the plane and then I break out the trimming chart.

The reason why you want 130 to 140 percent is to get the max resolution from the servo(s).

Now all of this is for a more experienced pilot and although can be beneficial to the new pilot I agree that it's not something that is needed or should be used until a bunch of experience AND confidence is gained.