Some mixes can cause differences when used in the opposite direction, but those are usually incurred in a vertical attitude. Even those are not much of an issue when set up correctly, such as mix on with throttle, mix triggering to no mix with zero or reduced throttle.
Most of mixing is in understanding what needs to be done, and in what amounts. It takes time, many,many trim flights, and often a little help. The most useful help you will have will be with someone to take notes as you fly all the trim flights. Mental notes all to often get lost during the landing approach
