It was Taken out of UMK 3. It was a Pointless thing to to in MK 3.
. The spin has a limit of 1 usage per combo, and 1 hit before it is locked, breakable to 2, for example (aaHPHPgc) Spin after a teleport punch on male ninjas. In MK3 he could spin twice in a row for no particular reason but that was removed. The Saw Blade is disabled while the spin, wobble, or drop out duration of the Spin Dash is active, this was also changed from MK3.
In order to do the double spin (in mk3), you have to wait until they are in the dizzy animation. It still combos but it's blockable at that point. You can do it unblockable if they are airborne. You can't do it like the CPU does.