Gates help your accuracy on true manuals, and ensure you only shift one gear at a time on the IS. Look at the IS shifter. For "M-D" it's a straight line left-to-right. In "D" you can't come down at all. In "M", it's a straight line down to "3" but no further. To "2" requires a right to the stop then again a straight line down only to "2". And finally a right to "L".