Of course all Exrtra models are not equal. I have not flown the CA model so I cant comment on the typical mixes. Also, pitch couple with rudder is a function of many things, one big one being CG, and many things need to be considered when properly trimming out an airplane.
Thats being said, lets assume you need mix and I'll answer your question.

Personaly, I set mixes like this so they are always on. If the model needs a lot of mix, I suppose it could act adversly in T rolls, hammers etc, but a good model wont need a lot of mix, unless you are running a very aft or forward CG.

Other mixes you could need are rudder (master) to aileron to mix out roll couple. The model could roll either way, proversly (with rudder) or adversly (away from rudder). That is primnarily a function of the amount of dihedral in the model. Like mix for pitch, I leave that on all of the time as well.

Other mix you could need is down elevaotr to throttle. This is done to correct for a model that does not track perfectly straight down. A lot of scale aerobatic designs tend to hint toward their top side (pull out) on a downline. To fix this you can mix in a small amount of down elevator that comes in with the last 2 clicks of low throttle. Start with about 1% mix. I just leave tha one on all the time as well.

With all mixes, first fly your model unmixed, and then add mix as needed. The mix values will probaby be unique for each model.