Not familiar with the specifics of what Pratt is doing, but GE/CFM bowed rotor mitigation logic is based on the residual EGT when the next start is initiated.
Subtle things can affect that - the downwind engine will cool slower, as will having one engine closer to the terminal or other building...
Engine guys hate single engine taxi - yes it can save a little fuel burn during taxi (and brake wear in some cases), but I often wonder about it's long term cost benefits. Nice, long cool down times at idle are highly beneficial to engine health.